There is no lack of evidence indicating a recent warming in the Earth's climate system. Thermometer readings show a steady increase in earth’s global average temperature over the past 100 years—January 2007, for example, was the world’s hottest January on record. Tide gauges reveal that sea level is rising due to glacial ice melt and thermal expansion of ocean waters. Ice core data reveals atmospheric CO2 concentrations are at their highest levels in more than 650,000 years, with dramatic increases confirmed by direct measurement since the Industrial Revolution. Moreover, these observed changes can be attributed to human activities, such as the burning of fossil fuels (oil, coal, and natural gas) and certain land-use practices. According to the Intergovernmental Panel on Climate Change (IPCC), “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations…” (IPCC, 2007, Summary for Policymakers, Working Group I).
Climate change is already having a measurable effect on our planet. But what are the effects of climate change? What is happening now, and, perhaps more importantly, what might happen 100 years into the future? In some cases, humanity's impact on Earth's climate is crystal clear and can be seen from direct observations of the environment. Some aspects of climate have not been observed to change - but scientists are working to determine the consequences and risks that humans might face if global greenhouse gas emissions are not reduced in the near future. To explore this topic more fully, click on the links below for short summaries recently covered by the IPCC's Working Group
Summary for Policymakers Report.
The full Working Group I report can be accessed here.
Summary of the IPCC’s Working Group I findings:
Rising Concentration of Atmospheric Green House Gases
Direct Observations of Recent Climate Change (pdf)
Some Aspects of Climate Change Have Not Been Observed to Change
Natural Variability versus Human-Induced Change
Projections of Future Climate Change
Below: Researchers reset weather recording equipment used in studies that focus on global climate change. Photo courtesy USDA.