Is the world's weather already out of control? Is the pollution of the past decades having an impact on the present? That's exactly what the United Nations' Intergovernmental Panel on Climate Change fears: Human influences over the last 30 years "have had a recognizable effect on many physical and biological systems," write the authors of the as yet unreleased second part of the 2007 global climate change report.

According to information obtained by SPIEGEL ONLINE, the Intergovernmental Panel on Climate Change (IPCC) is convinced global warming is already making the world sweat. At least that's the gist of the "Summary for Policymakers" from the group made up of hundreds of scientists.

The second part of the report is to be presented in April in Brussels after final discussions with government representatives from around the globe. The meta-study is certain to have a major political impact on the ongoing debate about climate change.

Mounting evidence: Climate change is happening now

The main conclusion of the report is that climate change is already having a profound effect on all the continents and on many of the Earth's ecosystems. The draft presents a long list of evidence:

• Glacial lakes are increasing in both size and number, potentially leading to deadly floods
• Permafrost in mountainous regions and at high latitudes is warming increasing the danger of land slides.
• As the temperature of rivers and lakes rises, their thermal stratification and water quality is changing.
• River currents, affected by melting glaciers and ice, are speeding up during the spring.
• Springtime is starting earlier, causing plants to bloom earlier and changing the migrations of birds.
• Many plants and animals are expanding their habitats into mountainous regions and higher latitudes that are becoming milder.

The authors of the report have sifted through some 30,000 data sets from more than 70 international studies documenting changes to water circulation, to cryospheres (ice zones), as well as to flora and fauna over a period of at least 20 years.

According to the IPCC, "more than 85 percent" of the data show "changes in a direction that would be expected as a reaction to warming." In other words: Researchers found evidence of environmental changes due to the greenhouse effect caused by mankind in nearly 9 out of 10 cases surveyed.

The researchers consider it "very unlikely" that the changes observed could be naturally occurring phenomena. They argue that the patterns of regional climate warming and environmental changes match up well with each other. And a similar consistency exists between the scientists' observations and what climate models have predicted would happen as temperatures rise.

Nature under threat

The UN experts go beyond the current situation. They also explore how populated regions and ecosystems will develop in the future as the world becomes warmer.

Many natural resources are likely to fall victim to climate change according to the IPCC draft report:

• Some 20 to 30 percent of all species face a "high risk of extinction" should average global temperatures rise another 1.5 to 2.5 degrees Celsius from their 1990 levels. That could happen by 2050, the report warns.
• Coral reefs are "likely to undergo strong declines."
• Salt marshes and mangrove forests could disappear as sea levels rise.
• Tropical rainforests will be replaced by savanna in those regions where groundwater decreases.
• Migratory birds and mammals will suffer as vegetation zones in the Artic shift.

The IPCC expects the following world regions to suffer the most due to climate change:

• The Arctic due to the greatest relative warming
• Small island states in the Pacific as sea levels rise
• Africa south of the Sahel zone due to drought
• Densely populated river deltas in Asia amid flooding

This list alone makes abundantly clear that mankind will not escape these changes unscathed.

Heat-related deaths, floods, drought, storms

The UN climate panel expects "increasing deaths, injuries and illness from heat waves, floods, storms, forest fires and droughts." The draft summary for policymakers details "heat-related mortality" especially in Europe and Asia.

Several hundred million people in densely populated coastal regions -- particularly river deltas in Asia -- are threatened by rising sea levels and the increasing risk of flooding. More than one-sixth of the world's population lives in areas affected by water sources from glaciers and snow pack that will "very likely" disappear, according to the report.

The climate experts detail the potential consequences for most of the world including Europe, Africa, Asia, the Americas, Australia, New Zealand, polar regions and small Pacific islands. For the most part, global warming will have negative effects for both humans and the environment across much of the planet. The positive aspects -- such as better agricultural and forestry yields in northern Europe -- will be more than outweighed by the threats presented by rising temperatures and the perils that accompany them.

The draft also makes clear just how strongly the authors stand behind their forecasts. Most of their conclusions belong to category two, which means the researchers back them with "strong certainty." Some are even designated "very strong certainty," including the example that North America will be hit by stronger forest fires and heat waves in large cities, as well as the assumption that climate change poses the biggest risk to small island states.

More food in the north and a possibly greener Earth

The report also lists specific positive developments due to global warming -- but they are expected to be of an ephemeral nature.

The experts apparently do not have concerns about the planet's food production capabilities. Conditions for agriculture are likely to improve in higher latitudes, leading to greater global yields overall. However, numerous developing countries are likely to be hit by greater periods of drought at the same time -- thus threatening their populations with hunger. The climate panel expects yields in the north and deep south only to begin to sink once temperatures rise by more than three degrees Celsius. Overall, they put "average trust" in their predictions about food production.

Rising carbon dioxide concentrations in the Earth's atmosphere will at first help the plant world. Vegetation growth will be stronger and the planet will become greener. The absorption of CO2 by plant life will to a certain extent work against climate change, but not forever. "In the second half of the century terrestrial ecosystems will become a source of carbon which will then accelerate climate change," the IPCC report warns.

The ability of the world's oceans to absorb CO2 is also expected to be depleted by the end of the 21st century. By then they could begin to release greenhouse gases instead of absorbing them.

Rich nations also at risk

Although the inhabitants of poorer, developing nations are likely to suffer the most from climate change, the IPCC report makes clear that richer industrial nations such as the United States are also at risk. North America, the report cautions, is hardly prepared for the "growing risks and economic losses caused by rising seas, storms and floods." The IPCC report also explicitly details the threat posed by tropical storms. Climate change is expected to increase the number of strong hurricanes leading to the concern that insurance companies might refuse to cover damages in regions threatened by such storms like New Orleans and the rest of the Gulf of Mexico.

Just as they did in the first part of the IPCC report released in February, the climate experts warn that air pollution and greenhouse gases are likely to have long-lasting effects since the planet's climate reacts slowly to changes. It's already a "fait accompli" that average temperatures near ground level will rise a further 0.6 degrees Celsius by 2100, according to the report. Humanity will have no choice but to adapt to the global changes.

According to information obtained by SPIEGEL ONLINE at the end of February, the climate panel will demand radical changes and massive investment against global warming in the third part of the IPCC report expected to be released in May in Bangkok. Some $16 billion (€12.1 billion) will be required by 2030 and humanity only has until 2020 to turn back the trend.

Whether the summary for policymakers will be released in its current form is unclear. Delegates from several countries wrestled with the wording of the first part of the report up until the last minute before its publication. Because, of course, for both scientists and politicians it can make a big difference whether the consequences of climate change are "likely," "very likely," or "practically certain."