Verbatim: Climate change to cause food shortages, mass extinctions, flooding

U.S. Geological Survey Follow Shriveled and Cracked  When USGS mapped the glaciers in Icy Bay, Alaska in the 1950s, the glacier in this image was flat and hundreds of meters thick. Bedrock is emerging as Guyot retreats very rapidly. Taken in Jan 2010. Credit: Shad O'Neel, USGS.
ICY BAY, Alaska, 2010 — Alaska glaciers like Guyot, above, have changed dramatically since the U.S. Geological Survey set out to map them in the 1950s. At the time, said the survey, the glacier above was flat and hundreds of meters thick. This recent photo reveals bedrock. Photo by Shad O’Neel, USGS, Public Domain



Climate change caused by humans will result in food shortages, mass extinctions and flooding, warns the world body of climate experts in its most comprehensive report yet, signed in Bonn on November 2, 2014. The Intergovernmental Panel on Climate Change says the science is now 95 per cent conclusive, that today’s climate change is unprecedented, and warns that the world must act, together and immediately, on adaptation and mitigation. It says some changes are already inevitable and the risk of not acting is extreme.


The Intergovernmental Panel on Climate Change (IPCC) is the world body for assessing the science related to climate change.  It was set up in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP), and endorsed by the United Nations General Assembly, to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation.

The IPCC assesses the thousands of scientific papers published each year to inform policymakers about what we know and don’t know about the risks related to climate change. The IPCC identifies where there is agreement in the scientific community, where there are differences of opinion, and where further research is needed.


Globally, including in the IPCC’s 195 member countries.


The IPCC’s 5th report was released November 2, 2014; global climate change meetings are scheduled for December and next year.  


Climate change respects no physical or human-made borders. The report’s key message is that climate change “exposes people, societies, economic sectors and ecosystems to risk …. high risk can result not only from high probability outcomes, but also from low probability outcomes with very severe consequences.” An imperfect ability to predict outcomes should not prevent them from being considered.

The IPCC’s fifth report on climate change draws, it says, on a “larger knowledge base of scientific, technical, and socio-economic literature” than any previous report since it was formed in 1988. It concludes that climate change risks are so certain and grave, states Christiana Figueres, Executive Secretary of the UN Framework Convention on Climate Change, that “to not act collaboratively and in a timely manner would fly in the face of both reason and responsibility.”

She called growing awareness of the crisis the good news: “governments everywhere have been increasingly internalizing and acting upon the IPCC’s findings as have cities, investors, companies and citizens ranging from environmental groups to faith-based organizations.”

All agencies and the scientific community “recognize that knowledge gaps remain and that further research is needed,” said a press statement from UNEP Executive Director Achim Steiner. “But the empirical evidence is not only sufficient to judge the risks of inaction; it is also compelling in terms of the many co-benefits of acting now to maintain a reasonable chance of limiting global warming to below 2°C.”

The UNEP release calls climate change “not only a challenge and a cost, but is also an opportunity to move towards a more inclusive green economy in which measures deliver both immediate benefits in terms of reducing emissions and multiple benefits in improvements in public health, energy efficiency, food security and the ability to invest in mitigation measures while adapting to climate impacts and building long-term resilience.”

Barriers to “green” outcomes include a lack of adequate, large-scale financial incentives, said the UNEP statement. The good news, it added, is “significant public and private investments are beginning to flow into energy efficiency; up to US$365 billion in 2012, with US$254 billion entering the renewable energy sector in the same year. 

The IPCC report is broken into four topic areas:

  1. Observed evidence for a changing climate, the impacts caused by this change and the human contributions to it.
  2. Projections of future climate change, projected impacts and risks.
  3. Adaptation and mitigation as complementary strategies for reducing and managing the risks
  4. Individual adaptation and mitigation options and policy approaches, with other societal objectives.

The report is dense, and includes figures and a stream of qualifications, including the level of confidence it has in each statement. It’s the product of a diverse and international committee, and so reading with a salt shaker in hand is recommended: it will have been subjected to influences from economic coercion to bullhorn diplomacy. But it’s also highly readable and, especially considering the many and diverse voices behind it, it is a shocking, and sobering, warning to humanity.

— Deborah Jones



Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.

Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.

Anthropogenic greenhouse gas emissions have increased since the pre-industrial era driven largely by economic and population growth . From 2000 to 2010 emissions were the highest in history. Historical emissions have driven atmospheric concentrations of carbon dioxide, methane and nitrous oxide, to levels that are unprecedented in at least the last 800,000 years, leading to an uptake of energy by the climate system.

The evidence for human influence on the climate system has grown since (the IPCC’s fourth report). Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, and in global mean sea-level rise; and it is extremely likely to have been the dominant cause of the observed warming since the mid-20th century. In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate.

In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate.

Changes in many extreme weather and climate events have been observed since about 1950. Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions.

Surface temperature is projected to rise over the 21st century under all assessed emission scenarios. It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions. The ocean will continue to warm and acidify, and global mean sea level to rise.

Climate change will amplify existing risks and create new risks for natural and human systems. Risks are unevenly distributed and are generally greater for disadvantaged people and communities in countries at all levels of development. Increasing magnitudes of warming increase the likelihood of severe, pervasive, and irreversible impacts for people, species and ecosystems. Continued high emissions would lead to mostly negative impacts for biodiversity, ecosystem services, and economic development and amplify risks for livelihoods and for food and human security.

Until mid-century, projected climate change will impact human health mainly by exacerbating health problems that already exist (very high confidence). Throughout the 21st century, climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income, as compared to a baseline without climate change (high confidence). Health impacts include greater likelihood of injury and death due to more intense heat waves and fires, increased risks from foodborne and waterborne diseases, and loss of work capacity and reduced labour productivity in vulnerable populations (high confidence). Risks of undernutrition in poor regions will increase (high confidence). Risks from vector-borne diseases are projected to generally increase with warming, due to the extension of the infection area and season, despite reductions in some areas that become too hot for disease vectors (medium confidence). Globally, the magnitude and severity of negative impacts will increasingly outweigh positive impacts (high confidence). By 2100 for RCP8.5, the combination of high temperature and humidity in some areas for parts of the year is expected to compromise common human activities, including growing food and working outdoors

In urban areas, climate change is projected to increase risks for people, assets, economies and ecosystems, including risks from heat stress, storms and extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, water scarcity, sea-level rise and storm surges (very high confidence).

Rural areas are expected to experience major impacts on water availability and supply, food security, infrastructure, and agricultural incomes, including shifts in the production areas of food and non-food crops around the world (high confidence). These impacts will disproportionately affect the welfare of the poor in rural areas, such as female-headed households and those with limited access to land, modern agricultural inputs, infrastructure, and education.

Aggregate economic losses accelerate with increasing temperature (limited evidence, high agreement) but global economic impacts from climate change are currently difficult to estimate. With recognized limitations, the existing incomplete estimates of global annual economic losses for warming of ~2.5 °C above pre-industrial levels are 0.2% to 2.0% of income (medium evidence, medium agreement). Changes in population, age structure, income, technology, relative prices, lifestyle, regulation, and governance are projected to have relatively larger impacts than climate change, for most economic sectors (medium evidence, high agreement). More severe and/or frequent weather hazards are projected to increase disaster- related losses and loss variability, posing challenges for affordable insurance, particularly in developing countries. International dimensions such as trade and relations among states are also important for understanding the risks of climate change at regional scales.

From a poverty perspective, climate change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security, and prolong existing poverty traps and create new ones, the latter particularly in urban areas and emerging hotspots of hunger (medium confidence). Climate change impacts are expected to exacerbate poverty in most developing countries and create new poverty pockets in countries with increasing inequality, in both developed and developing countries.

Climate change is projected to increase displacement of people (medium evidence, high agreement). Displacement risk increases when populations that lack the resources for planned migration experience higher exposure to extreme weather events, such as floods and droughts. Expanding opportunities for mobility can reduce vulnerability for such populations. 

Climate change can indirectly increase risks of violent conflict by amplifying well-documented drivers of these conflicts, such as poverty and economic shocks.

Many aspects of climate change and its impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases.

 Without additional mitigation efforts beyond those in place today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread, and irreversible impacts globally (high confidence). Mitigation involves some level of co-benefits and of risks due to adverse side-effects, but these risks do not involve the same possibility of severe, widespread, and irreversible impacts as risks from climate change, increasing the benefits from near-term mitigation efforts. 

Mitigation and adaptation are complementary approaches for reducing risks of climate change impacts. They interact with one another and reduce risks over different timescales (high confidence). Benefits from adaptation can already be realized in addressing current risks, and can be realized in the future for addressing emerging risks. Adaptation has the potential to reduce climate change impacts over the next few decades, while mitigation has relatively little influence on climate outcomes over this timescale. Near- term and longer-term mitigation and adaptation, as well as development pathways, will determine the risks of climate change beyond mid-century. The potential for adaptation differs across sectors and will be limited by institutional and capacity constraints, increasing the long-term benefits of mitigation (high confidence). The level of mitigation will influence the rate and magnitude of climate change, and greater rates and magnitude of climate change increase the likelihood of exceeding adaptation limits (high confidence).

Without additional mitigation efforts beyond those in place today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread and irreversible impacts, globally (high confidence).

Climate change poses an increasing threat to equitable and sustainable development (high confidence). Some climate-related impacts on development are already being observed. Climate change is a threat multiplier. It exacerbates other threats to social and natural systems, placing additional burdens particularly on the poor and constraining possible development paths for all. Development along current global pathways can contribute to climate risk and vulnerability, further eroding the basis for sustainable development.

Many adaptation and mitigation options can help address climate change, but no single option is sufficient by itself. Effective implementation depends on policies and cooperation at all scales, and can be enhanced through integrated responses that link mitigation and adaptation with other societal objectives.

Adaptation and mitigation responses are underpinned by common enabling factors. These include effective institutions and governance, innovation and investments in environmentally sound technologies and infrastructure, sustainable livelihoods, and behavioural and lifestyle choices.

In many countries, the private sector plays central roles in the processes that lead to emissions as well as to mitigation and adaptation. Within appropriate enabling environments, the private sector, along with the public sector, can play an important role in financing mitigation and adaptation (medium evidence, high agreement). The share of total mitigation finance from the private sector, acknowledging data limitations, is estimated to be on average between two-thirds and three-fourths on the global level (2010-2012) (limited evidence, medium agreement). In many countries, public finance interventions by governments and international development banks encourage climate investments by the private sector and provide finance where private sector investment is limited. The quality of a country’s enabling environment includes the effectiveness of its institutions, regulations and guidelines regarding the private sector, security of property rights, credibility of policies and other factors that have a substantial impact on whether private firms invest in new technologies and infrastructures. Dedicated policy instruments and financial arrangements, for example, credit insurance, feed-in tariffs, concessional finance or rebates provide an incentive for mitigation investment by improving the return adjusted for the risk for private actors. Public- private risk reduction initiatives (such as in the context of insurance systems) and economic diversification are examples of adaptation action enabling and relying on private sector participation.”



IPCC home site:


Approval of the Synthesis of Assessment Report 5 of the Intergovernmental Panel on Climate Change (IPCC), and Statement by Christiana Figueres, Executive Secretary of the UN Framework Convention on Climate Change, November 2, 2014:

Adoption of Latest IPCC Climate Science Sets World for Crucial Lima Talks, Underlines Urgent Need for Bold Political Agreement: press statement from UNEP,



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