Sea level rise

Sea level rise

With increasing average global temperature, the water in the oceans expands in volume, and additional water enters them which had previously been locked up on land in glaciers, for example, the Greenland and the Antarctic ice sheets. An increase of 1.5 to 4.5 °C is estimated to lead to an increase of 15 to 95 cm (IPCC 2001).

The sea level has risen more than 120 metres since the peak of the last ice age about 18,000 years ago. The bulk of that occurred before 6000 years ago. From 3000 years ago to the start of the 19th century, sea level was almost constant, rising at 0.1 to 0.2 mm/yr; since 1900, the level has risen at an average of 1.7 mm/yr; since 1993, satellite altimetry from TOPEX/Poseidon indicates a rate of about 3 mm/yr.

In a paper published 18th May 2007, the climatologist, James Hansen presented new evidence. George Monbiot, a British journalist, summarises his findings as follows:

"The IPCC predicts that sea levels could rise by as much as 59 cm this century. Hansen’s paper argues that the slow melting of ice sheets the panel expects doesn’t fit the data. The geological record suggests that ice at the poles does not melt in a gradual and linear fashion, but flips suddenly from one state to another. When temperatures increased to 2-3 degrees above today’s level 3.5 million years ago, sea levels rose not by 59 centimetres but by 25 metres. The ice responded immediately to changes in temperature.

Effects of global warming

The predicted effects of global warming on the environment and for human life are numerous and varied. It is generally difficult to attribute specific natural phenomena to long-term causes, but some effects of recent climate change may already be occurring. Raising sea levels, glacier retreat, Arctic shrinkage, and altered patterns of agriculture are cited as direct consequences, but predictions for secondary and regional effects include extreme weather events, an expansion of tropical diseases, changes in the timing of seasonal patterns in ecosystems, and drastic economic impact. Concerns have led to political activism advocating proposals to mitigate, eliminate, or adapt to it.

The 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) includes a summary of the expected effects.

Global Warming

Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-twentieth century and its projected continuation.

The average global air temperature near the Earth's surface increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the hundred years ending in 2005. The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations"via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.

These basic conclusions have been endorsed by at least thirty scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. While individual scientists have voiced disagreement with some findings of the IPCC, the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.

Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century.^[1] The range of values results from the use of differing scenarios of future greenhouse gas emissions as well as models with differing climate sensitivity. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a thousand years even if greenhouse gas levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the oceans.^[1]

Increasing global temperature will cause sea level to rise, and is expected to increase the intensity of extreme weather events and to change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, trade routes, glacier retreat, species extinctions and increases in the ranges of disease vectors.

Remaining scientific uncertainties include the amount of warming expected in the future, and how warming and related changes will vary from region to region around the globe. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions, but there is ongoing political and public debate worldwide regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences

Emissions Irrelevant To Future Climate Change

Emissions Irrelevant To Future Climate Change

Climate change and the carbon emissions seem inextricably linked. However, new research published in BioMed Central's open access journal Carbon Balance and Management suggests that this may not always hold true, although it may be some time before we reach this saturation point.

The land and the oceans contain significantly more carbon than the atmosphere, and exchange carbon dioxide with the atmosphere. The amount of CO2 emissions absorbed by the land or the oceans vary in response to changes in climate (including natural variations such as El Nino or volcanic eruptions). So current theories suggest that climate change will have a feedback effect on the rate that atmospheric CO2 increases; rising CO2 levels in turn add to global warming.

The link between the carbon cycle, and human effects caused by emissions, energy use and agriculture, may only be relevant for the next 'several centuries,' suggest Igor Mokhov and Alexey Eliseev from the A.M. Obukhov Institute of Atmospheric Physics RAS, in Moscow, Russia. The authors used a climate model known as IAP RAS CM to study how feedback between our climate and the carbon cycle changes over time. In their simulations, the authors assumed that fossil fuel emissions would grow exponentially with a characteristic timescale from 50 to 250 years.

In their models, Mokhov and Eliseev found that although climate-carbon cycle feedback grows initially, it then peaks and eventually decreases to a point where the feedback ceases. If we succeed in slowing down the rate of emissions, the peak would be reached much later. However, a steep increase in emissions would bring the peak in coupling between climate and carbon emissions even closer.

The authors suggest that we are heading inexorably towards the saturation peak, irrespective of how quickly we get there: "Even weak but continuing emissions lead to eventual saturation of the climate-carbon cycle feedback," Mokhov and Eliseev explain.

History of Earth Day

Earth Day -- April 22 -- each year marks the anniversary of the birth of the modern environmental movement in 1970.

Among other things, 1970 in the United States brought with it the Kent State shootings, the advent of fiber optics, "Bridge Over Troubled Water," Apollo 13, the Beatles' last album, the death of Jimi Hendrix, the birth of Mariah Carey, and the meltdown of fuel rods in the Savannah River nuclear plant near Aiken, South Carolina -- an incident not acknowledged for 18 years.

Participant in Earth Day, 1970. Photo: EPA History Office

It was into such a world that the very first Earth Day was born.

Earth Day founder Gaylord Nelson, then a U.S. Senator from Wisconsin, proposed the first nationwide environmental protest "to shake up the political establishment and force this issue onto the national agenda. " "It was a gamble," he recalls, "but it worked."

At the time, Americans were slurping leaded gas through massive V8 sedans. Industry belched out smoke and sludge with little fear of legal consequences or bad press. Air pollution was commonly accepted as the smell of prosperity. Environment was a word that appeared more often in spelling bees than on the evening news.

Earth Day 1970 turned that all around.

On April 22, 20 million Americans took to the streets, parks, and auditoriums to demonstrate for a healthy, sustainable environment. Denis Hayes, the national coordinator, and his youthful staff organized massive coast-to-coast rallies. Thousands of colleges and universities organized protests against the deterioration of the environment. Groups that had been fighting against oil spills, polluting factories and power plants, raw sewage, toxic dumps, pesticides, freeways, the loss of wilderness, and the extinction of wildlife suddenly realized they shared common values.

Earth Day 1970 achieved a rare political alignment, enlisting support from Republicans and Democrats, rich and poor, city slickers and farmers, tycoons and labor leaders. The first Earth Day led to the creation of the United States Environmental Protection Agency and the passage of the Clean Air, Clean Water, and Endangered Species acts.

Sen. Nelson was awarded the Presidential Medal of Freedom -- the highest honor given to civilians in the United States -- for his role as Earth Day founder.

As 1990 approached, a group of environmental leaders asked Denis Hayes to organize another big campaign. This time, Earth Day went global, mobilizing 200 million people in 141 countries and lifting the status of environmental issues on to the world stage. Earth Day 1990 gave a huge boost to recycling efforts worldwide and helped pave the way for the 1992 United Nations Earth Summit in Rio de Janeiro.

As the millennium approached, Hayes agreed to spearhead another campaign, this time focused on global warming and a push for clean energy. Earth Day 2000 combined the big-picture feistiness of the first Earth Day with the international grassroots activism of Earth Day 1990. For 2000, Earth Day had the Internet to help link activists around the world. By the time April 22 rolled around, 5,000 environmental groups around the world were on board, reaching out to hundreds of millions of people in a record 184 countries. Events varied: A talking drum chain traveled from village to village in Gabon, Africa, for example, while hundreds of thousands of people gathered on the National Mall in Washington, D.C., USA.

EPA Administrator William K. Reilly with former Senator Gaylord Nelson, Earth Day 1990. Photo: EPA History Office

Earth Day 2000 sent the message loud and clear that citizens the world 'round wanted quick and decisive action on clean energy.

Now, the fight for a clean environment continues. We invite you to be a part of this history and a part of Earth Day. Discover energy you didn't even know you had. Feel it rumble through the grass roots under your feet and the technology at your fingertips. Channel it into building a clean, healthy, diverse world for generations to come.

sourch by earthdaynetwork