Climate change is already affecting the planet and society and will continue to do so for generations to come. The physical and chemical changes of human activities are being felt in natural ecosystems on land and at sea, on farms and ranches, and in cities and suburbs, but the changes are not happening uniformly. Differences in how regions are affected by varying degrees of warming, precipitation, and changes of animal and plant species are likely to get even more extreme as climate change continues. Some areas may actually get a bit cooler for a while! Similarly for rainfall, some parts of the planet will get drier, while others will get more precipitation in more extreme events.
The poles have already seen the greatest warming, and will continue to warm more rapidly than other areas. Already we’re seeing record losses of ice in the Arctic. That melting ice contributes to rising sea levels, affecting the entire planet. In addition, warm water expands, so sea levels will rise as the atmosphere warms. The ocean has risen 4-8 inches (10-20 centimeters) globally over the last hundred years. As sea level continues to rise, flooding and storm surges will threaten freshwater sources, as well as coastal homes and buildings. Coastal facilities and barrier islands in many parts of the world are gradually submerging, and some low-lying islands have already had to be evacuated, as Australia’s The Age (July 29, 2009) describes happening in the Carteret Islands of Papua New Guinea.
As climate change causes the ocean to rise, increased atmospheric carbon dioxide is also changing ocean chemistry. When carbon dioxide dissolves in water, it makes water more acidic. Warmer ocean water also contain less oxygen. These changes harm marine ecosystems, destroying coral reefs that shelter much of the ocean’s biodiversity, and harming many other species. In addition to the harmful effects on natural ecosystems, this affects fish that people eat, coral reefs that tourists visit, and the whales, dolphins, sharks, and other marine life that fascinate so many people. Climate change and changing oceanic chemistry affect the tiny plankton in the ocean which produce much of the oxygen in our air, as researchers Graeme Hays, Anthony Richardson, and Carol Robinson explained (PDF) in a 2005 review in Trends in Ecology and Evolution. Changes to the growth of these tiny organisms have surprisingly large effects on global climate, as do climate change-induced changes to the movements of marine life, as reported by Wired magazine (July 2009). Changing ocean chemistry thus has complex and unpredictable effects on global climate and even the air we breathe. In 2005, the Royal Society issued (PDF) a detailed report for policymakers in the United Kingdom examining the ways climate change and ocean acidification would affect the oceans.
Freshwater resources are being affected as well, with winter snowpack and mountain glaciers that provide water declining in many parts of the world. Climate change — especially droughts and desertification — is likely to increase the demands on those water supplies even as they fade away.
The frequency of extreme weather events is increasing through the warming and moistening of the atmosphere. Hot days are becoming even hotter and more frequent, and both drought and heavy rain and snow will continue to occur more often. Because hurricanes draw their strength from the heat of water on the ocean’s surface, a warmer climate means hurricanes have been getting stronger. Researchers work to understand how these changes to the weather affect coastal populations, not to mention shipping, fishing, and other industries in those waters.
Changes in rainfall and temperature will alter where various plants and animals can live, forcing some species to migrate, disrupting delicate ecosystems, and increasing the rate of extinctions globally. Scientists are studying how different species responded to past climate changes, hoping to better understand the impacts of today’s climate change on wildlife. Already, hunters and anglers are seeing changes in migration patterns and animal behavior, and gardeners and farmers see plants sprouting, flowering, and losing their leaves at different times, forcing them to change what they can plant. Historic droughts are forcing farmers to plant different crops, and some farmland is becoming unusable.
As climate change causes plants and animals to relocate, disease will also move, exposing human populations — and crop plants, livestock, and wildlife — to new diseases. Climate change also affects human health and mortality, with the Environmental Protection Agency and the Centers for Disease Control warning about direct effects from rising temperatures, degraded air quality, and greater risks from Lyme disease, hantavirus, and other diseases carried by insects and animals. Drought, degraded air and water quality, and greater hazards in coastal and low-lying regions will, as the World Health Organization points out, create additional health problems, especially among the populations most vulnerable to natural hazards and disease.
As leaders in the U.S. military recognize (for instance in the 2007 National Research Council Report National Security Implications of Climate Change for U.S. Naval Forces), the effects of climate change will affect the security of nations as conflicts brew over competition for water, food, and land. The prospect of large groups of climate refugees migrating across borders is a concern for governments as well as for organizations devoted to reducing risk and helping those who are living in poverty and in vulnerable regions.
The insurance industry is already planning for the effects of climate change, which will often occur as natural hazards, such as floods, fires, heat waves, and droughts. Insurance regulators have demanded that insurers in the United States report their risks from climate change, with one regulator saying, “Climate change will have huge impacts on the insurance industry and we need better information on how insurers are responding to the challenge.” Reinsurers, the companies that insure insurance companies, are also watching these consequences. Munich Re, one of the largest reinsurers, keeps a database of natural disasters, and finds, “The high number of weather-related natural catastrophes and record temperatures both globally and in different regions of the world provide further indications of advancing climate change.” Other leading insurance and finance companies have commissioned reports to evaluate the risks and opportunities created by climate change.
Many researchers work to develop detailed predictions about the effects of climate change in local areas, and to make those predictions available to the general public. Predicting the long-term consequences is complicated in part because choices we make as individuals and as a society will change those outcomes. By reducing the amount of carbon dioxide and other heat-trapping gases in the atmosphere, the effects will be less severe than if we choose to increase the amounts of those gases. This is one reason it’s so important to learn all we can about climate change: to make informed choices about the climate, and prepare for the results of those choices.
- Global Climate Change Impacts on the United States, a 2009 report from the United States Global Change Research Program summarizing the impacts of climate change based on data from across the United States government.
- Climate Change 2007: Impacts, Adaptation, and Vulnerability, a major report from the Intergovernmental Panel on Climate Change, an international organization that periodically brings together scientists to evaluate the state of climate science, reviewing the evidence of how climate change in affecting society and the natural world. The Summary for Policymakers (PDF) is especially accessible.
- Insurance in a Climate of Change, a collection of resources and reports on how climate change is affecting the insurance industry, and what the industry can do to prevent and prepare for climate change, from researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory.
- Storm World: Hurricanes, Politics, and the Battle Over Global Warming, journalist Chris Mooney’s look inside the scientific community’s investigation of the effects of climate change on hurricanes.