Warming that has already occurred is affecting weather patterns, damaging marine and coastal ecosystems, affecting the Polar Regions and forest ecosystems, and altering crop yields.

Evidence of change: IPCC Report 2007

Observations and data from 1961 show that the average global ocean temperature has increased. The ocean has been absorbing more than 80% of the heat we have added to the climate system so far. Mountain glaciers and snow ice have declined on average in both hemispheres The warming of the oceans and melting ice caps has contributed to sea level rise. Up to 1993, global average sea level rose at a rate of 1.8 [1.3 – 2.3] mm per year. From 1993 to 2003, the rate was faster, at 3.1 [2.4 - 3.8] mm per year More intense and longer droughts have been observed since the 1970’s Cold days, cold nights and frost have become less frequent, while hot days, hot nights and heat waves have become more frequent. All of the ten warmest years on record have occurred since 1990 Many species have been moving poleward by around six kilometers per decade since 1970. Changing seasonal events, with flowering and egg-laying occurring 2-3 days earlier each decade, in the Northern Hemisphere.

For more information see the IPCC report.

Varying degrees of impacts are predicted for varying temperatures. On average, the earth will become warmer. According to the latest IPCC report, even current levels of greenhouse gases in the atmosphere are likely to result in:

Extreme weather events: There are clear indicators that impacts in many sectors will become more and more severe with rising temperatures

Declining crop yields: which could leave millions without the ability to produce or purchase food

Ocean acidification: would affect not just marine systems, but also fish stocks - an already over-extracted resource

Melting glaciers: and rising seas will displace people, submerge cities and lead to salinity of precious arable land. Melting ice sheets are predicted to raise sea levels and threaten at least 4 million km² of land

Biodiversity loss: changing climate affects species, ecosystems and ecosystem functions. Some ecosystems are more vulnerable to the negative impacts of climate change than others. In fact, some of the most vulnerable ecosystems are also the richest in biodiversity - wetlands, coastal ecosystems and tropical forests.

Effects would include severe threat to our food and water security, increased droughts, floods, hurricanes and storms, displacement of coastal populations, increased and changed patterns of diseases².

To achieve this will require urgent, substantial action from both developed and developing countries. For a start, to avoid the most serious consequences, we will have to peak our emissions no later than 2015, and rapidly reduce emissions after that by 50 to 80% below 2000 levels by the year 2050¹⁸ .