The are diverse and potentially very large. They constitute most serious long term environmental issues currently facing the world. The risks of adverse impact from Climate increase with the magnitude of climate change. Health, eco-systems, agriculture, water and major sectors will bear these impacts. Negative impacts on unique of threatened species and risks from extreme climate event occurs with a temporary change as small as 10C and these impacts and risks are projected to become significant and widespread for changes of 20C to 30C.
Above 20C temperature increase, the vast majority of market impacts are predicted to be negative and most regions will suffer adverse affects form climate change. Risks from large-scale discontinuities become significant above a 30 C temperature change.
It is believed that changes of up to 10C might be beneficial for a few regions and sectors such as agriculture in mid to high latitudes. A number of new impacts like recent change in the acidity of the ocean, reducing its capacity as a carbon sink are also visible. Global temperature rise of about 1.50C may be a threshold that triggers melting of Greenland ice-cap. The serious risk of large scale, irreversible systems disruption as changes to thermo- circulation, reversal of the land carbon sink and possible of the Antarctica ice sheets is more likely above 30C.
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| >30 C |
| will increase premature mortality by several hundred thousands excluding events like heat waves. | |||
| 10% of ecosystem areas worldwide will shift. | worldwide. | due to climate change likely above 20%, and much more in some regions. Global losses of coastal wetlands may exceed 10%. | |
| and US) yields increases for up to 20C temperature rise, but beyond this decline. | a 30C rise a group of developing countries with a population of 2 billion will see the food deficit double. | ||
| major catastrophic. BetweenC and 4.50C potential to trigger melting of the West Antarctic Ice sheet eventually raising sea levels by further 5-6m. | shutdown up to 50% or above. |