Earth's temperature could rise by more than 4°C by 2100, claim scientists

Research by the University of New South Wales found that the global climate is more affected by carbon dioxide than previously thought

The scientists believe temperatures could rise by more than 8 °C by 2200 if C02 emissions are not reduced

Global temperatures could soar by at least 4°C by 2100 if carbon dioxide emissions aren’t slashed, new research warns.



Climate scientists claim that temperatures could rise by at least 4 °C by 2100 and potentially more than 8 °C by 2200, which could have disastrous results for the planet.



The research, published in the journal Nature, found that the global climate is more affected by carbon dioxide than previously thought.

Scientists added that temperatures could rise by more than 8°C by 2200 if CO2 emissions are not reduced. The research found that the global climate is more affected by carbon dioxide than previously thought

HOW CLOUDS AFFECT THE CLIMATE

Fewer clouds form as the planet warms so that less sunlight is reflected back into space, driving temperature on Earth higher.

When water evaporates from oceans, vapour can rise nine miles into the atmosphere to create rain clouds that reflect light, or can rise just a few miles and drift back down without forming clouds.

While both processes occur in the real world, current climate models place too much emphasis on the amount of clouds that form on a daily basis.

By looking at how clouds form in on the planet , scientists are able to create more realistic climate models, which are used to predict future temperatures.

Scientists have long debated how clouds affect global warming.

It could also solve one of the mysteries of climate sensitivity - the role of cloud formation and whether it has positive or negative effect on global warming.

Researchers now believe that existing climate models significantly overestimate the number of clouds protecting our atmosphere from overheating.

The study suggests that fewer clouds form as the planet warms, so that less sunlight is reflected back into space, driving temperatures up on Earth.

Professor Steven Sherwood, from the University of New South Wales, said: 'Our research has shown climate models indicating a low temperature response to a doubling of carbon dioxide from pre-industrial times are not reproducing the correct processes that lead to cloud formation.'



'When the processes are correct in the climate models, the level of climate sensitivity is far higher.

Protective: Researchers now believe that existing climate models significantly overestimate the number of clouds protecting the atmosphere from overheating

'Previously, estimates of the sensitivity of global temperature to a doubling of carbon dioxide ranged from 1.5 °C to 5 °C .

'This new research takes away the lower end of climate sensitivity estimates, meaning that global average temperatures will increase by 3°C to 5°C with a doubling of carbon dioxide.'

Professor Sherwood told The Guardian that a rise of 4 ° C would likely be 'catastrophic' rather than just dangerous.

'For example, it would make life difficult, if not impossible, in much of the tropics, and would guarantee the eventual melting of the Greenland ice sheet and some of the Antarctic ice sheet' he said.



COST OF EXTREME WEATHER EVENTS SOARS BY 60 PER CENT IN 30 YEARS

The costs of extreme weather events have risen dramatically, climate scientists warned last week. T he national science academies of EU Member States believe Europe needs to plan for future probabilities of extreme weather, such as heat waves, floods and storms. Highlighting a 60 per cent rise over the last 30 years in the cost of damage from extreme weather events across Europe, the European Academies' Science Advisory Council (EASAC) warned of the grave economic and social consequences if European policy makers do not use the latest estimates of future droughts, floods and storms in their planning while adapting to global warming and the resulting climate disruption. The report urges EU nations to prepare for heat waves and think about how to reduce the number of deaths. Flood defence is also an area that requires improvement, as rising sea levels will leave coastal areas at serious risk from storm surges. Researchers also believe climate research and adaptation plans should be given more priority.

The key to this narrower but higher estimate can be found by looking at the role of water vapour in cloud formation.

When water vapour is taken up by the atmosphere through evaporation, the updraughts can rise up to nine miles (15km) and form clouds that produce heavy rains.

The can however also rise just a few kilometres before returning to the surface without forming rain clouds, which reflect light away from the earth's surface.

When they rise only a few kilometres, they reduce total cloud cover because they pull more vapour away from the higher clouds forming.

Researchers found that climate models predicting a lesser rise in the Earth's temperature, do not include enough of the lower level water vapour process.

Most models show nearly all updraughts rising to 9 miles and forming clouds, reflecting more sunlight and as a result, the global temperature in these models becomes less sensitive in its response to atmospheric carbon dioxide.

The scientists warned that such a rise in temperatures on Earth would lead to droughts (pictured) and make life difficult for people living in the tropics. A hotter planet would also likely lead to the melting of the Greenland ice sheet and some of the Antarctic ice sheet

When the models are made more realistic, the water vapour is taken to a wider range of heights in the atmosphere, causing fewer clouds to form as the climate warms.

This increases the amount of sunlight and heat entering the atmosphere and as a result increases the sensitivity of our climate to carbon dioxide or any other perturbation.

The result is that when the models are correct, the doubling of carbon dioxide expected in the next 50 years will see a temperature increase of at least 4°C by 2100.

Professor Sherwood said: 'Climate sceptics like to criticise climate models for getting things wrong and we are the first to admit they are not perfect, but what we are finding is that the mistakes are being made by those models that predict less warming, not those that predict more.

