Climate change: forecast for 2100 is floods and heat ... and it’s man’s fault

By Nick Allen

9:04PM BST 16 Aug 2013

Climate scientists have concluded that temperatures could jump by up to 5°C and sea levels could rise by up to 82 cm by the end of the century, according to a leaked draft of a United Nations (UN) report.

The UN Intergovernmental Panel on Climate Change (IPCC) also said there was a 95 per cent likelihood that global warming is caused by human activities. That was the highest assessment so far from the IPCC, which put the figure at 90 per cent in a previous report in 2007, 66 per cent in 2001, and just over 50 per cent in 1995.

Reto Knutti, a professor at the Swiss Federal Institute of Technology in Zurich, said: “We have got quite a bit more certain that climate change is largely man-made. We’re less certain than many would hope about the local impacts.” The IPCC report, the first of three in 2013 and 2014, will face intense scrutiny particularly after errors in the 2007 study, which wrongly predicted that all Himalayan glaciers could melt by 2035.

Almost 200 governments have agreed to try to limit global warming to below 2°C above pre-industrial times, which is seen as a threshold for dangerous changes including more droughts, extinctions, floods and rising seas that could swamp coastal regions and island nations. Temperatures have already risen by 0.8°C since the Industrial Revolution.

The report will say there is a high risk global temperatures will rise by more than 2°C this century. They could rise anywhere from about 0.6°C to almost 5°C a wider range at both ends of the scale than predicted in the 2007 report. It will also say evidence of rising sea levels is “unequivocal”. The report projects seas will rise by between 30 cm and 82 cm by the late 21st century. In 2007 the estimated rise was between 18 cm and 58 cm, but that did not fully account for changes in Antarctica and Greenland.

Scientists say it is harder to predict local impacts. Drew Shindell, a Nasa scientist, said: “I talk to people in regional power planning. They ask, 'What’s the temperature going to be in this region in the next 20 to 30 years, because that’s where our power grid is?’ We can’t really tell.”

(adapted from <telegraph.co.uk>)

1. Scientists think it is 95% likely that human activity is causing global warming.
2. Temperatures could be 5°C warmer by the end of the current century.
3. Sea levels are not likely to be higher than today by the end of the century.
4. Scientists are surer now than in 2007 that humans are causing global warming.
5. 50% of the scientists believed humans were the cause of climate change in 1995.

Um microscópio composto é constituído, em sua forma mais simples, por duas lentes convergentes colocadas em sequência, conforme esquematizado na figura abaixo. A lente mais próxima ao objeto é chamada objetiva e a lente mais próxima ao olho humano é chamada ocular. A imagem formada pela objetiva é real, maior e invertida, e serve como objeto para a ocular, que forma uma imagem virtual, direita e maior com relação à imagem formada pela objetiva. Suponha que a distância focal da lente objetiva seja 1 cm, a distância focal da lente ocular seja 4 cm e a distância entre as lentes seja de 6 cm.

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