Half of the world's wetlands were lost last century. Logging and conversion have shrunk the world's forests by as much as half. Some 9 percent of the world's tree species are at risk of extinction; tropical deforestation may exceedsquare kilometers per year. Fishing fleets are 40 percent larger than the ocean can sustain.
Global Change Research Program reported in June  that: Observations show that warming of the climate is unequivocal.
The global warming observed over the past 50 years is due primarily to human-induced emissions of heat-trapping gases. These emissions come mainly from the A poll on global warming of fossil fuels coal, oil, and gaswith important contributions from the clearing of forests, agricultural practices, and other activities.
The report, which is about the effects that climate change is having in the United States, also said: Climate-related changes have already been observed globally and in the United States. These include increases in air and water temperatures, reduced frost days, increased frequency and intensity of heavy downpours, a rise in sea level, and reduced snow cover, glaciers, permafrost, and sea ice.
A longer ice-free period on lakes and rivers, lengthening of the growing season, and increased water vapor in the atmosphere have also been observed. Some of the changes have been faster than previous assessments had suggested.
Human activities, primarily the burning of fossil fuels coal, oil, and natural gasand secondarily the clearing of land, have increased the concentration of carbon dioxide, methane, and other heat-trapping "greenhouse" gases in the atmosphere There is international scientific consensus that most of the warming observed over the last 50 years is attributable to human activities.
Avoiding dangerous climate change There is an extensive discussion in the scientific literature on what policies might be effective in responding to climate change. In general, however, risk increases A poll on global warming increases in both the rate and the magnitude of climate change.
This article mostly focuses on the views of natural scientists.
However, social scientists,  medical experts,  engineers  and philosophers  have also commented on climate change science and policies. Climate change policy is discussed in several articles: Statements by scientific organizations of national or international standing[ edit ] See also: The California Governor's Office website lists nearly worldwide scientific organizations hold the position that climate change has been caused by human action.
The 34 national science academy statements include 33 who have signed joint science academy statements and one individual declaration by the Polish Academy of Sciences in Joint national science academy statements[ edit ] Following the publication of the IPCC Third Assessment Reportseventeen national science academies issued a joint statement, entitled "The Science of Climate Change", explicitly acknowledging the IPCC position as representing the scientific consensus on climate change science.
The statement stresses that the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action, and explicitly endorsed the IPCC consensus. Following the IPCC Fourth Assessment Reportthe declaration states, "It is unequivocal that the climate is changing, and it is very likely that this is predominantly caused by the increasing human interference with the atmosphere.
These changes will transform the environmental conditions on Earth unless counter-measures are taken. A consensus, based on current evidence, now exists within the global scientific community that human activities are the main source of climate change and that the burning of fossil fuels is largely responsible for driving this change.
The IPCC should be congratulated for the contribution it has made to public understanding of the nexus that exists between energy, climate and sustainability. It is essential that world leaders agree on the emission reductions needed to combat negative consequences of anthropogenic climate change".
The statement references the IPCC's Fourth Assessment ofand asserts that "climate change is happening even faster than previously estimated; global CO2 emissions since have been higher than even the highest predictions, Arctic sea ice has been melting at rates much faster than predicted, and the rise in the sea level has become more rapid.
Problems of global warming, climate change, and their various negative impacts on human life and on the functioning of entire societies are one of the most dramatic challenges of modern times. PAS General Assembly calls on the national scientific communities and the national government to actively support Polish participation in this important endeavor.
The scientific evidence is clear: The pace of change and the evidence of harm have increased markedly over the last five years. The time to control greenhouse gas emissions is now. Global climate change is real and measurable To reduce the global net economic, environmental and social losses in the face of these impacts, the policy objective must remain squarely focused on returning greenhouse gas concentrations to near pre-industrial levels through the reduction of emissions.
The spatial and temporal fingerprint of warming can be traced to increasing greenhouse gas concentrations in the atmosphere, which are a direct result of burning fossil fuels, broad-scale deforestation and other human activity. An Analysis of Some Key Questions.
The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability.
Human-induced warming and associated sea level rises are expected to continue through the 21st century The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue.
The globe is warming because of increasing greenhouse gas emissions. Measurements show that greenhouse gas concentrations in the atmosphere are well above levels seen for many thousands of years.
Further global climate changes are predicted, with impacts expected to become more costly as time progresses. Reducing future impacts of climate change will require substantial reductions of greenhouse gas emissions.
According to the Telegraph"The most prestigious group of scientists in the country was forced to act after fellows complained that doubts over man made global warming were not being communicated to the public".NBC News/Wall Street Journal Poll conducted by Hart Research Associates (D) and Public Opinion Strategies (R).June , N=1, adults nationwide.
Margin of. Jun 06, · Rasmussen Reports is a media company specializing in the collection, publication and distribution of public opinion information.. We conduct public opinion polls on a . The best opinions, comments and analysis from The Telegraph. Paul MacRae, June 24, Most geologists aren’t part of Al Gore’s “ per cent consensus” of scientists that humans are the principal cause of global warming and .
Ahead of a major scientific report on global warming to be released next week, David Brancaccio talks with Laurie David, a producer of the Oscar-nominated documentary "An Inconvenient Truth" and a. Dr. Ivar Giaever, a Nobel Prize-Winner for physics in , declared his dissent on man-made global warming claims at a Nobel forum on July 1, “I would say that basically global warming is a non-problem,” Dr.
Giaever announced during his speech titled “Global Warming Revisited.