Climate Reports: Recent Analyses

A number of respected organizations, both domestically and internationally, have continued to fill the pipeline of valuable information resources on all aspects of climate change. Those reports are expected to feed prominently into continued international negotiations on confronting climate change challenges, in particular, for instance, a scheduled meeting in Paris in December 2015.

A fair question for those lacking the time or need to follow each new study in great detail is “Where to start?”

This Climate Brief approaches that question by reviewing four of the most important, and most respected and influential, recent sets of analyses. It begins at the global level, which in essential ways provided substantive material for the reports that followed. It then reviews two leading studies that divided the US into regions and evaluated the projected impacts in each region and in key sectors of those regions.

It concludes with a look at another report that also took a sector approach – in this case, that sector involving military preparedness and national security. A key point in that report is that consideration solely of likely region-by-region impacts and potential mitigation and adaptation strategies is not sufficient on its own because projected impacts “transcend international borders and geographic areas of responsibility.” That military-oriented report also finds that climate change can no longer be viewed solely as a “threat multiplier,” but that climate change impacts now must be seen also as “catalysts” for instability and conflict.

The IPCC 2014 Fifth Assessment Report

Because a number of studies inevitably are influenced by and draw from the most recent report from the United Nations\World Meteorological Organization Intergovernmental Panel on Climate Change (IPCC), the 2014 Fifth Assessment Report, “AR5,” is a logical place to start.

But that in itself can be a heavy lift. The full report, the work of hundreds of scientists from around the world organized into three working groups, totals nearly 5,000 pages, with assessments of some 30,000 individual scientific papers.

Haven’t the time to plow through 5,000 pages? A good place to start may not even involve reading all or even part of the 2014 Fifth Assessment Report, but rather watching a 16-minute video of the IPCC’s “Synthesis Report” described by the IPCC chairman as a “roadmap” of the group’s scientific work.

That IPCC video concludes that “warming of the climate system is unequivocal” and it says that since the 1950s “many of the observed changes are unprecedented over decades and millennia.” As examples, it points to warmer atmospheric and ocean temperatures, diminished Arctic sea ice and rising sea levels. Concentration of greenhouse gases in the atmosphere has increased by 40 percent compared with pre-industrial times, says the IPCC video, and levels of carbon dioxide in the atmosphere, which the report attributes primarily to burning of fossil fuels, are higher than at any time in the past 800,000 years, with most of the current adverse impacts particularly obvious in the coldest reaches of the planet.

While IPCC by definition focuses on the global and international scale, its reports increasingly reflect also input from the more “granular” analyses of the scientific papers assessed: Those that increasingly try to discern potential impacts from a warming climate at a more regional level. It’s long been understood that the narrower the geographic area being analyzed, the more difficult the scientific analyses.

Once having reviewed the IPCC video, a recommended second-stop on one’s excursion through the IPCC Fifth Assessment Report might well be the “Summary for Policymakers,” a 34-page official document encapsulating, in nontechnical language, overall details of the full report.

Climate-Related Risks Facing North America

“Risks will vary through time across regions and populations,” IPCC wrote in its 2014 “Summary for Policymakers,” dependent on myriad factors including the extent of adaptation and mitigation. Its Working Group II Technical Summary Section B-3 extensively summarizes projected regional impacts.

For North America, IPCC pointed to three “key risks” as justifying “high confidence” in the findings:

  • Wildfire-induced loss of ecosystem integrity, property loss, human morbidity and mortality as a result of increased drying trend and temperature trend;
  • Heat-related human mortality, and;
  • Urban floods in riverine and coastal areas, inducing property and infrastructure damage; supply chain, ecosystem, and social system disruption; public health impacts; and water quality impairment, due to sea level rise, extreme precipitation, and cyclones.

For the first of those three categories, the report notes that some ecosystems “are more fire-adapted than others” and that forestry managers and municipal planners “are increasingly incorporating fire protection measures (e.g., prescribed burning, introduction of resilient vegetation),” but that institutional capacity to support ecosystem application “is limited.”

For the second of those North America “key risk” categories, involving heat-related human mortality, the report said residential air conditioning “can effectively reduce risk.” But it noted that availability and use of air conditioning varies widely and is subject to complete blackouts in power outages. “Vulnerable populations include athletes and outdoor workers” who can’t easily access air conditioning, it noted. The report points to somewhat helpful adaptation measures such as reducing exposure to heat extremes and also to early heat-warming systems and cooling centers.

In adapting to the third “key risk” mentioned above, the IPCC 2014 notes the expense and disruptive impacts of effectively managing urban drainage issues while identifying “low-regret” and “co-benefit” aspects of using less impervious surfaces along with more green infrastructure and rooftop gardens. It said that outdated rainfall design standards in many areas “need to be updated to reflect current conditions” and pointed out that wetlands conservation efforts and prudent land-use planning “can reduce the intensity of flood events.”

A more detailed examination of IPCC’s 2014 assessment of regional risks and adaptation possibilities can be found at Technical Summary Section B-3 and Working Group II Fifth Assessment Report Part B: Regional Aspects.

Climate-Related Risks by Sector

In examining individual sectors and how they might be affected by climate change, IPCC AR5 said some existing climate-related risks will be amplified in a warmer climate and some “new risks” will arise, in some cases with what it called “cascading effects.” Not all of the projected impacts will be adverse, it added: “To a lesser extent” there will be “some potential benefits.”

Freshwater Resources

Pointing to “robust evidence,” IPCC said there is “high agreement” that climate change risks will “increase significantly with increasing greenhouse gas concentrations.” It said the percentage of the global population experiencing “water scarcity” and “major river floods” have increased as a result of warming over the 21st century. It pointed to a significant reduction in surface- and ground-water resources in most dry subtropical regions and, with somewhat less confidence, to intensifying competition among various sectors for water.

“Climate change is projected to reduce raw water quality and pose risks to drinking water quality even with conventional treatment, due to interacting factors: increased temperature; increased sediment, nutrient, and pollutant loadings from heavy rainfall; increased concentrations of pollutants during droughts; and disruption of treatment facilities during floods.”

The scientists said they have “limited experience, high agreement” involving prospects that adaptive water management techniques (scenario planning, learning-based approaches, and flexible and low-regret solutions) can help build resilience to some of the “uncertain hydrologic changes and impacts” projected for a warmer world.

Terrestrial and Freshwater Ecosystems

The IPCC AR5 scientists pointed to their “high confidence” that “a large fraction of both terrestrial and freshwater species faces increased extinction risk under projected climate change” during and beyond the 21st century. That is the prognosis “especially as climate change interacts with other stressors, such as habitat modification, over-exploitation, pollution, and invasive species.”

Under mid-to high rates of projected climate change, “many species will be unable to track suitable climates,” they said, even as “some species will adapt.” Those unable to adequately adapt face extinction in part or all of their ranges, they said. They expressed “high confidence” that efforts such as maintaining genetic diversity, helping species migrate and disperse, and manipulating “disturbance regimes” such as fires and floods and other stressors “can reduce, but not eliminate, risks of climate change-related impacts.”

Coastal Systems and Low-Lying Areas

Projected sea level rise through the 21st century means coastal systems and low-lying areas “will increasingly experience adverse impacts such as submergence, coastal flooding, and coastal erosion,” the IPCC AR5 reports, with the involved scientists pointing to their “high confidence” in that conclusion. Population growth and increased economic development and urbanization along the coasts are at the heart of that conclusion, but adaptation costs will vary widely among regions and countries, with some low-lying developing countries and small island states facing the most serious risks.

Marine Systems

Redistribution of global marine-species and loss of marine biodiversity in sensitive regions “will challenge the sustained provision of fisheries productivity and other ecosystem services,” AR5 scientists reported with “high confidence.” They reported that for medium- to high-emission scenarios, “ocean acidification poses substantial risks to marine ecosystems,” particularly those in polar ecosystems and coral reefs.

Food Security and Food Production Systems

For major crops such as wheat, rice and maize, the AR5 scientists reported with “medium confidence” that climate change across tropical and temperate regions, in the absence of adaptation successes, will lead to reduced production for local temperature increases of 3.6°degrees F (2C) or more above late-20th-century levels,” with individual locations actually benefiting. They pointed to increased inter-annual variability of crop yields in many regions “in the context of rapidly rising crop demand.”

“All aspects of food security are potentially affected by climate change, including food access, utilization, and price stability,” they said with “high confidence.” They pointed to risks of reduced supplies, lower incomes, and fewer employment opportunities in tropical countries. They pointed to “large risks to food security globally and regionally” if global temperature increases by 7.2 degrees F (~4C) or more above late-20th-century levels.

Urban Areas

With “very high confidence,” the AR5 scientists concluded that “heat stress, extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, and water scarcity pose risks in urban areas for people, assets, economies, and ecosystems.” Those lacking adequate infrastructure and services or living in “poor quality housing and exposed areas” face the most serious risks.

Rural Areas

“Major adverse impacts are projected in the near term and beyond” for rural areas, which will result from reduced water availability and supply, food security problems, diminished agricultural incomes, and shifts in global production areas of food and non-food crops. Most likely to be disproportionately affected are rural poor, female-headed households and those having limited access to land, modern agricultural options, suitable infrastructure and education. The AR5 authors said they have “medium confidence” that trade reform and investment strategies and consideration of “rural decision-making contexts” can improve market access for some small-scale farms.

Key Economic Sectors and Services

The AR5 authors pointed to a number of factors they believe will be “large relative to the impacts of climate change” for most economic sectors, specifically identifying population, age structure, income, technology, relative prices, lifestyle, regulation, and governance.” They wrote that climate change will reduce energy demand for heating and increase it for cooling in residential and commercial sectors, and affect energy sources and technologies in different ways depending on resources and locations involved. Insurers will face increased challenges offering affordable coverage.

“Global economic impacts from climate change are difficult to estimate,” they said, with estimates depending on countless assumptions (many of which are disputable) and disparate estimates of damages, tipping points and other factors. They pointed to “large differences between and within countries” and estimates varying widely based on assumed damages and use of different discount rates.

Human Health

The AR5 authors projected human health impacts until mid-century based on “exacerbating health problems that already exist.” Throughout the 21st century, they wrote that they have “high confidence” that ill health will increase in many regions and especially in developing countries with low income. They pointed to more heat waves and wild fires, increased under-nutrition as a result of lower food production in poor regions, lost work capacity and lower labor productivity in vulnerable populations, and increased risks from food- and water-borne diseases as sources of concern.

They also pointed to some “positive effects” for public health (reduced cold-related mortality and morbidity in some regions), but they say they have “high confidence” globally and throughout the 21st century that “the magnitude and severity of negative impacts are projected to increasingly outweigh positive impacts.”

With a high-emissions scenario and higher global temperature and humidity, they pointed to “compromise[d] normal human activities, including growing food or working outdoors” by the year 2100.

Human Security

This is a category often called “national security,” but the IPCC AR5 authors labeled it “human security.” Their conclusions may sound familiar to those who have followed climate change and national security issues.

Increased prospects for forced migrations, or “displacement,” are in the cards for groups lacking planned migration resources or experiencing high exposure to extreme weather events in rural or urban areas, particularly in low-income developing countries, the authors write, pointing to “medium evidence” but “high confidence.” They wrote that under the high-emission scenario, higher temperatures and humidity in some areas are important factors.

They cautioned too of increased risks of violent conflicts (civil war or inter-group violence) as climate change can amplify “well-documented drivers of these conflicts” such as poverty and economic shocks. “Multiple lines of evidence relate climate variability to these forms of conflict,” they wrote.

In addition, they pointed to indirect but increased risks facing critical infrastructure and territorial integrity of many states. “For example, land inundation due to sea level rise poses risks to the territorial integrity of small island states and states with extensive coastlines.” They point to “transboundary impacts” such as changes in sea ice and shared resources as increasing rivalry among states.

Livelihoods and Poverty

Slower economic growth is likely throughout the 21st century in a changing climate, the authors wrote, and reducing poverty will be even more difficult. Reduced food security and longer and new “poverty traps,” particularly in urban areas and “emerging hotspots of hunger,” will also pose challenges.

Worsened poverty in developing countries and “new poverty pockets in countries with increasing inequality” are likely with wage-labor-dependent poor households facing challenges from increasing food prices, particularly in regions of high food insecurity and high inequality.


The Global is Local. Or Is It Really?

All of which makes for important, sobering and well-documented reading. But what does it mean in my – or to you more importantly your – backyard? And in the disparate backyards of millions of Americans regularly turning on their television sets and using their digital apps not so much to learn about the global climate, but rather to learn about the local weather? To understand, in effect, how to dress that day, whether to carry or leave behind their umbrellas or jackets? Whether that long-awaited outdoor event is likely to be held…or rescheduled?

A one-time Speaker of the U.S. House of Representatives, Tip O’Neill of Massachusetts, is perhaps best remembered for his oft-cited line that “all politics is local.” The same applies to weather.

And it’s in that very area that a number of the more recent academic and scientific reports on impacts of climate change appear to be making substantial progress.


The 2014 National Climate Assessment

In the third of the National Climate Assessments (NCA) published by federal science agencies, the U.S. Global Change Research Program, USGCRP, pointed to several “noteworthy advances” since publication of its second NCA in 2009:

  • “Continued warming and an increased understanding of the U.S. temperature record, as well as multiple other sources of evidence, have strengthened our confidence in the conclusions that the warming trend is clear and primarily the result of human activities. For the contiguous United States, the last decade was the warmest on record, and 2012 was the warmest year on record. [Editor’s note: NASA and NOAA now say that 2014 is the warmest year on record.]
  • Heavy precipitation and extreme heat events are increasing in a manner consistent with model projections; the risks of such extreme events will rise in the future.
  • The sharp decline in summer Arctic sea ice has continued, is unprecedented, and is consistent with human-induced climate change. A new record for minimum area of Arctic sea ice was set in 2012. [Editor’s note: that 2012 record for minimum area of Arctic sea ice was not exceeded in 2013.]
  • A longer and better-quality history of sea level rise has increased confidence that recent trends are unusual and human-induced. Limited knowledge of ice sheet dynamics leads to a broad range for projected sea level rise over this century.
  • New approaches to building scenarios of the future have allowed for investigations of the implications of larger reductions in heat trapping gas emissions than examined previously.”

The 2014 NCA makes significant forward strides in expressing how various large geographic regions of the U.S. may be affected by projected climate change. In addition, in an effort to make its findings accessible and understandable to a broad non-technical audience, the report provides for each region a set of brief bulleted “key messages” summarizing the more detailed chapters on each of those regions. Those key point synopses provide a convenient way to get into the details of potential impacts in each region.


Heat waves and coastal and river flooding are projected as posing “a growing challenge” and “increase the vulnerability of residents of the Northeast, in particular already disadvantaged populations. Climate-related hazards, including sea level rise, coastal flooding and intense precipitation, are seen compromising infrastructure, and agriculture, fisheries, and ecosystems “will be increasingly compromised over the next century.”

Farmer adaptations involving planting of new crops “are not cost- or risk-free,” the report notes, and adaptive capacity, varying across the region, “could be overwhelmed by a changing climate.”

The report notes that a number of states and “a rapidly growing number of municipalities” across the region have begun incorporating climate change risks into their planning, but “implementation of adaptation measures is still at early stages.”

Southeast and the Caribbean

Natural and built environments and the regional economy face “widespread and continuing threats” from projected sea level rise, the report finds. Public health, natural and built environments, and the region’s energy, agricultural and forestry sectors are likely to experience increasing temperatures along with more frequent, intense and longer extreme heat anomalies. The study points to the region’s continuing population growth, changes in land-use patterns and increased competition for water – all coming in the context of decreased water availability in a warmer and drier climate – as challenges not only for the region’s economy, but also for its “unique ecosystems.”


The “next few decades” may bring some increased crop yields as a result of rising carbon dioxide levels and longer growing seasons, but “those benefits will be progressively offset” as a result of extreme weather events, the report says. Agricultural productivity is expected to decrease over the long term even if aggressive adaptation efforts reduce some detrimental effects.

Many tree species across the region are expected to migrate northward in the face of rising temperatures, reducing the ability of the region’s forests to absorb carbon, and residents will face increased public health risks from more intense and more frequent heat waves, increased humidity, and degraded air and water quality.

The report points to an increased number of extreme rainfall and flooding events over the past century “and these trends are expected to continue, causing erosion, declining water quality, and negative impacts on transportation, agriculture, human health, and infrastructure.” It sees an increased “range of risks” for the Great Lakes – changes in range and distribution of some fish species, more invasive species and harmful algal blooms, and impairments of beaches. Commercial navigation season may lengthen with declines in ice coverage.

Great Plains

Demand for water and energy is expected to increase as a result of warmer temperatures in parts of the Great Plains, constraining development, stressing natural resources and increasing competition for water among community, farming, energy production and ecological needs.

Warmer winters likely will lead to changes in crop growth cycles and changes in timing and magnitude of rainfall events” have already been observed.” Those trends are expected to continue, requiring adoption of new approaches to farming and livestock management.

The 2014 NCA report concludes that increased fragmentation of landscape, particularly in the context of energy development in the northern stretch of the Great Plains states, will interfere with some species’ adaptation efforts. Those areas now most vulnerable to weather extremes will experience additional stresses as a result of more frequent extreme events in “an already highly variable climate system.”

In general, the changes expected in the Great Plains states “will exceed those experienced in the last century,” the report says, and current adaptation and planning initiatives “are inadequate to respond to these projected impacts.”


Observed changes in snowmelt, leading to changes in timing of streamflows, are expected to lead to reduced water supplies and increased competition for water, “causing far-reaching ecological and socioeconomic consequences,” according to the 2014 NCA. Sea level rise, inundations, and erosion, along with increasing ocean acidity pose “a major threat” to the region’s infrastructure and habitats, it says.

Tree diseases “are already causing widespread tree die-off and are virtually certain to cause additional forest mortality over the next 25 to 30 years, significantly altering forest landscapes.” Under the higher energy-use scenarios examined, “extensive conversion of subalpine forests to other forest types is projected by the 2080s.”

As for agriculture across the Northwest, adaptation efforts can help offset some adverse impacts, but “critical concerns” involve adaptation costs, development of more climate-resilient technologies and management, and availability and timing of adequate water supplies.


Arctic summer ice, currently receding faster than had been projected, “is expected to virtually disappear before mid-century,” according to the 2014 NCA. Results will include changed marine ecosystems, increased shipping access, more opportunities for offshore development and more vulnerability to coastal erosion.

With most Alaska and British Columbia glaciers shrinking “substantially,” the report evaluates implications for hydropower production, ocean circulation patterns and global sea level rise. Continued thawing of permafrost in Alaska will cause drier landscapes, more wildfires, changes to wildlife habitat, higher costs for maintaining infrastructure and additional releases of greenhouse gases. Current and projected higher ocean temperatures and changes in ocean chemistry are projected to alter distribution and productivity of Alaska marine fisheries.

“The cumulative effects of climate change in Alaska strongly affect Native communities, which are highly vulnerable to these rapid changes but have a deep cultural history of adapting to change,” the report says.

Hawaii and U.S. Affiliated Pacific Islands

Increased coral bleaching and coral reef disease outbreaks, along with changed distribution of tuna fisheries, are anticipated, as is further ocean acidification and reductions in coral growth and health. Coral reef fish stocks will face particular challenges.

On many islands, already-constrained fresh water supplies are expected to become even more limited, and salt water intrusion resulting from sea level rise will impair fresh water quality and quantity, particularly on low islands.

With higher temperatures, lower rainfall totals in some areas will stress the region’s plants and animals and increase risks of extinctions, particularly in high-elevation ecosystems increasingly exposed to invasive species.

Coastal flooding and erosion likely will be exacerbated as a result of sea level rise, leading to more coastal flooding and erosion, risks to coastal ecosystems, infrastructure and agriculture. It all could lead to lower tourism revenues, the report advises.

The region’s “many unique customs, beliefs, and languages” will confront challenges as a result of increased threats to food and water security, infrastructure, health, and safety, increasing pressures for human migration, it says.

Oceans and Marine Resources

Continued increases in global ocean temperatures are expected to continue, with “large impacts” on climate, ocean circulation, chemistry and ecosystems. With continued ocean absorption of roughly one-quarter of human-caused carbon dioxide emissions, marine ecosystems face changes “in dramatic yet uncertain ways,” the report says.

“Significant” loss of habitat for many species and in many areas, including Arctic and coral reef ecosystems, are expected, but expansion of habitat in other areas, and for other species, also is expected. One result: alterations in distribution, abundance and productivity of many marine species.

More and different human and marine life diseases are expected as sea surface temperatures continue to increase, with risks extending to corals, abalones, oysters, fish and marine mammals. Costs of doing business are expected to increase in some cases, and public access to and enjoyment of ocean areas may be disrupted.

Coastal Zone Development and Ecosystems

Rising sea levels, storm surges, inland flooding, erosion and other impacts expected in a warmer climate pose challenges for coastal water supply, energy infrastructure and evacuation routes, the report says.

Ports, tourism and fishing sites in already-vulnerable coastal areas face increased risks from rising sea level, disrupted economic activity and higher costs for maintaining or relocating some assets. Displacement of vulnerable populations from vulnerable coastal areas will likely take place in the context of “socioeconomic disparities [that] create uneven exposures and sensitivities to growing coastal risks and limit adaptation options.”

Already substantially altered as a result of increasing populations and associated stresses, “further reduction or loss of the services” that coastal ecosystems provide pose substantial concerns…and “potentially irreversible impacts.”

While residents and leaders of many coastal regions “are increasingly aware” of the climate risks their communities face, the report says, “significant institutional, political, social, and economic obstacles to implementing adaptation actions remain.”


The Risky Business Project Report

In October 2013, three wealthy and well-known individuals launched the Risky Business Project to quantify and publicize economic risks posed by a changing climate.

Former New York City Mayor Michael R. Bloomberg, of Bloomberg Publishing and Bloomberg Philanthropies, joined with former U.S. Secretary of the Treasury Henry Paulson and billionaire climate activist Tom Steyer in a partnership, gaining financial support from a number of leading foundations. The stature and reputations of the three co-chairs and a number of other individuals they involved imbued their effort with a fair amount of credibility and appearance of stature and independence, paving the way for a lot of early media coverage.

In the group’s initial report, “The Economic Risks of Climate Change in the United States,” released in June 2014, the authors acknowledged drawing from and building on the work of the Intergovernmental Panel on Climate Change (IPCC) and the National Climate Assessment (NCA), and it adopts the regional approach outlined by NCA.

But it points too to a difference: “We went even deeper than the NCA, conducting analysis down to the county level in some cases, and also focusing on key economic sectors and showing the potential cost of these impacts within those regions and sectors.” (Another element distinguishing the approach of the Risky Business report from the NCA report is its consideration of “tail risks” – lower-probability but high-impact impacts.)

The report explains that “regions matter” because “in a country as large and diverse as the U.S., it does not make sense to aggregate the highly localized impacts of climate change into one headline number … Indeed, most economic successes and disasters in the U.S. happen at the individual metropolitan, state, and occasionally multi-state level.” Pointing also to the “cultural dimension” distinguishing one region from another, the report says “there may not be one single national response” to the risks presented by the changing climate. It says that for some living in the Southwest and Southeast – “which will likely experience the most extreme heat and sea level rise over this century” – there may be “no choice but to migrate to cooler and more livable areas, disrupting lives, livelihoods, and regional identities formed over generations.”


Sea level rise and effects on coastal infrastructure are expected to pose “the region’s major climate impact,” the Risky Business report says, noting also “a sizeable increase in temperatures and average number of extremely hot days over the course of the century.”

The report points to melting of land ice in the Antarctic and Greenland ice sheets and to “evidence of accelerating and perhaps unstoppable land ice melt in West Antarctica,” with lesser impacts resulting from groundwater withdrawals and land subsidence adjacent to the ocean.

The report says much of the region’s major cities and industries is located along the coastlines, with 88 percent of the Northeast’s population and 68 percent of its Gross Domestic Product generated in coastal counties. It warns of substantially rising sea levels for New York City, the New Jersey Shore, Boston and Portland, Maine “if we continue on our current path.”

“Our research shows that, if we continue on our current path, additional projected sea level rise will likely increase average annual property losses from hurricanes and other coastal storms by $6 billion to $11 billion over the course of the century.” Projected increased hurricane activity “would raise those estimates to $11 billion to $22 billion – a 2-to-4-fold increase from current levels,” it says.

Because many residents of the Northeast live in cities with populations of one-million or more and with warmer temperatures as a result of the “heat island effect,” the report says, the number experiencing “extremely hot” 95-degrees F days will increase. The number of days having that heat will also increase: “The average resident will likely see between 4.7 and 16 additional extremely hot days,” it says, up from 2.6 days per year. “By late century this range will likely jump to between 15 and 57 additional extremely hot days, or up to two additional months of extreme heat.” The report says the increasingly hot summers “will have serious negative effects on health, mortality, and labor productivity.”


The Southeast region, like the Northeast, has numerous coastal communities, but in the Southeast only 36 percent of residents live in coastal counties, and those counties account for 33 percent of the region’s total GDP, compared with the higher percentages in the Northeast.

But with New Orleans and Miami at or below sea level and with Miami “built on porous limestone that allows water inundation,” much of the Southeast’s highway, rail, port, airport and oil and gas infrastructure “sits at low elevations.”

Sea level rise adds up to “a significant risk” for the Southeast, with Norfolk, “home to the nation’s largest naval base,” facing sea level rise of 1.1 to 1.7 feet by mid-century,and of 2.5 to 4.4 feet by 2100. The report points to a 1-in-100 chance that sea level rise for Norfolk could exceed 7.1 feet by 2100.

In Florida, “even modest sea level rise comes at a significant economic cost” because major cities are built on porous limestone. The report concludes that current projections indicate $15 billion to $23 billion of existing property “will likely be underwater by 2050…and between $53 billion and $208 billion by the end of the century.”

Other risks highlighted for the Southeast: more flooding from hurricanes and other coastal storms, changes in hurricane activities, and between one and one-half to four additional months of extreme heat each year by 2100. In terms of mortality, the report points to 14 to 45 additional deaths per 100,000 people annually by 2100 – at the current population of the region, between 11,000 and 35,000 additional deaths per year.

[Editor’s Note: For those with an in-depth interest in climate impacts in the Southeast, an excellent resource is the Risky Business Project’s Come Heat and High Water: Climate Risk in the Southeastern U.S. and Texas.]


A particular sector of concern for the Risky Business discussion of the Midwest is commodity agriculture, with the region producing about 65 percent of the country’s corn and soybeans alone. It suggests that a “business as usual” scenario, with little significant adaptation by farmers, will lead Missouri and Illinois to face as much as a 15 percent likely average yield loss over the next 5 to 25 years, and a 73 percent loss by 2100.

On the other hand, the report’s authors see agricultural interests as “probably the best equipped to manage these risks.” Adequately informed and motivated, it says, they can mitigate impacts through double- and triple-cropping, seed modification, crop switching and other measures. In some cases, crop production can shift from the Midwest to the Upper Great Plains, Northwest, and Canada – aiding the U.S. and global food system but putting individual Midwest farmers and farm communities at risk as production moves to a cooler climate.

Beyond the region’s agricultural bounties, the report says its human residents will face increased risks from up an estimated 20 to 75 additional extreme-heat days by 2100. “On the other hand, the region will also experience fewer winter days with temperatures below freezing.”

The “real story” in the Midwest involves the Human Heat Stroke Index, measuring necessary evaporation of sweat from the skin. It cautions that the combination of high heat and high humidity across parts of the region could lead to body temperatures of “close to 104 degrees F, which is the body’s absolute limit” – a heat-plus-humidity measure “never experienced” in the U.S. and a point that will make it “functionally impossible to be outdoors.”

[Editor’s Note: For those with an in-depth interest in climate impacts in the Midwest, an excellent resource is the Risky Business Project’s Heat in the Heartland: Climate Change and Economic Risk in the Midwest.]

Great Plains

Stretching from Montana to Texas, the Great Plains is projected to experience impacts “very differently” from the northern border with Canada to the southern border with Mexico.

The group pointed to “an increase in extremely hot days” across Texas, Oklahoma and Kansas, with between three and four months of additional “extreme hot days” annually by 2100. Extremely cold days will decrease from around 159 annually below-freezing days now to between 117 and 143 by mid-century and between 70 and 122 by the end of the century.

Texas coastal communities, responsible for about one-third of the state’s GDP, will see sea levels rise in Galveston, for instance, by 1.5 to 2 feet by 2050…and by 3.2 to 4.9 feet by 2100, “with a 1-in-100 chance of more than a 7.6 foot rise.”

With agriculture and energy production dominating much of the Great Plains region, southern states may see declines, and northern states may see yield gains, as temperatures rise. Demand for air conditioning is likely to increase significantly, taxing the electricity power sector. Texas and Oklahoma, in particular, are expected to see the largest increases in electricity consumption, — up to 5 percent and 6 percent respectively over the next five to 25 years. Most of that increase will come during day-light hours already experiencing high demand and perhaps requiring construction of up to 95 gigawatts of additional power generation.

[Editor’s Note: For those with an in-depth interest in climate impacts in Texas, an excellent resource is the Risky Business Project’s Come Heat and High Water: Climate Risk in the Southeastern U.S. and Texas.]

Pacific Northwest

Expected sea level rise is “more varied” than on the East Coast, the report notes, and sea levels off Washington and Oregon coasts may actually decline, assuming melting of the West Antarctic does not occur any time soon.

With an economy depending heavily on its forests, “significant potential impacts,” including more and more severe wildfires, are a concern, both because of increased drought and because of wood damages resulting from pests surviving warmer winters.

The region’s residents are expected to experience an additional seven to 15 extremely hot days (95 degrees F) by 2100, a three- to eight-fold increase in number of hot days for the region and “a significant change from historic norms.”


“Already warm and dry,” the region incorporating California and the “traditional” southwestern states of Arizona, Colorado, Nevada, New Mexico and Utah “in some ways serves as a microcosm” of climate impacts likely across the mainland U.S. The region’s current 40 percent of area covered by desert is likely to increase in coming decades, the report says, with an additional 33 to 70 extremely hot days annually by 2100.

With 87 percent of Californians living in coastal counties, and those counties producing 80 percent of the state’s GDP lower-probability/higher-impact risks resulting from Antarctic melt are a particular concern. The strategic military importance of San Diego, for instance, faces a 1- in 100 chance of a 6.3 feet rise in sea level by 2100.

More hot and dry days across the region raise concerns of more wildfires and “drying up” of already stressed water supplies. With a warmer climate, “significantly less snow in the mountains” and a resulting decrease in spring runoff poses a problem, particularly for California and the Southern Rockies, threatening supplies of groundwater for “critical industries such as agriculture, as well as for simple drinking and bathing.” The report points also to increasing demand for air conditioning, noting that “electricity generation is heavily water-dependent,” and risks to non-commodity crops such as tree nuts and fruits.

[Editor’s Note: For those with an in-depth interest in climate impacts in California, an excellent resource is the Risky Business Project’s From Boom to Bust? Climate Risk in the Golden State.]


“Ground zero for U.S. climate impacts,” the Risky Business report says in introducing its Alaska discussion.

It points to oil and gas production, fisheries and tourism as key economic sectors, the latter two dependent on healthy oceans and coastal ecosystems.

Over the next century, the report points to average Alaska temperatures 3.9 to 8 degrees F warmer than over the past 40 years, and 7.6 to 16 degrees F warmer by 2100.

With a “tail-risk” one in-twenty chance of temperatures averaging as much as 19 degrees F warmer by 2100, the report finds that most of the warming will occur in winter months, “significantly decreasing” the number of extremely cold days.

The report says that 84 percent of Alaskans live in the state’s coastal counties, which produce 86 percent of the state’s GDP. Sea level is expected to vary and may decrease over the course of the century. The report anticipates sea level declines at Juneau; a change of minus 0.6 feet to plus 1.2 feet for Anchorage; and a rise of 2.3 to 4.5 feet rise for Prudhoe Bay by 2100…with a tail-risk one-in-one hundred chance of more than a 6.6 foot rise.


Hawaii is a 100 percent coastal state with 100 percent of its population and 100 percent of its GDP in coastal areas. Little wonder then that sea level rise in a “significantly warmer” climate is a major concern.

The “current path” leads to a sea level rise at Honolulu of 0.8 inches to 1.2 feet by 2050, and of 2.1 to 3.8 feet by 2100. The “tail risk” 1-in-100 prospect is for an increase of more than 6.9 feet by 2100, the report says.

Given the island state’s dependence on the U.S. mainland and “the rest of the world” for its food and energy, the Risky Business report says, Hawaiians “are by necessity very sensitive” to impacts that can affect global supply chains, and costs and availability, in other regions. The challenge there is that diversifying its energy needs and using more domestic renewable sources involve interests that themselves are on vulnerable coasts.


CNA Military Advisory Board ‘Accelerating Risks of Climate Change’ Report

In May 2014, a panel of 16 retired generals and admirals from the Army, Navy, Air Force and Marine Corps didn’t hold back in cautioning not only of “severe risks for our national security” from climate change but in also going further:

During our decades of experience in the U.S. military, we have addressed many national security challenges, from containment and deterrence of the Soviet nuclear threat during the Cold War to political extremism and transnational terrorism in recent years. The national security risks of projected climate change are as serious as any challenges we have faced.

They reported having reached that conclusion based in part on “lively, informative, and very sobering” discussions with a wide range of scientists, security analysts, industry executives and government and military officials. In the seven years since their earlier report on national security and climate change, they wrote, “in many cases the risks we identified are advancing noticeably faster than we anticipated.”

Their approach to considering regional impacts in an essential way is fundamentally different from the regional approaches taken by NCA and the Risky Business project. They cautioned that “thinking about how to manage the risks of projected climate change as just a regional problem or – worse yet – someone else’s problem may limit the ability to fully understand their consequences and cascading effects.”

Still not holding back, the retired brass said they are “dismayed that discussions of climate change have become so polarizing and have receded from the arena of informed discourse and debate.” They urged that political “posturing” and budgetary “woes” not inhibit consideration of an issue “so many believe to be a salient national security concern for our nation.”

The CNA Military Advisory Board report accepted a conclusion from the NCA report that climate change no longer be considered an issue for a “distant future” but rather an issue that “has moved firmly into the present.” The board in 2014 went beyond its 2007 conclusion pointing to effects of climate change as “threat multipliers that will aggravate stressors abroad such as poverty, environmental degradation, political instability, and social tensions – conditions that can enable terrorist activity and other forms of violence. Now, the group said, those issues must be seen as “catalysts for instability and conflict.”

The authors pointed to the Arctic as a “clear example” of a region of the world crying out for more international cooperation.

Given an increasingly complex and financially interdependent world, they said, “It is no longer adequate to think of projected climate impacts to any one region of the world in isolation. Climate change impacts transcend international borders and geographic areas of responsibility. Their report said projected climate change impacts will affect “all 16 critical infrastructure sectors identified in Homeland Security planning directives.”

About the Author

Morris A. (Bud) Ward, editor of Yale Climate Connections, is a proven and widely experienced communicator and educator on environmental, energy and climate change issues. He has an extensive publishing history including hundreds of bylined news and analysis articles and authorship or co-authorship of five professional books. He has conducted numerous first-hand workshops for reporters, editors and policy makers on issues involving journalism/communications, climate change and environmental risk. He writes, speaks and teaches regularly on issues related to climate change and on the changing nature of journalism and mass communications in modern society.