Problems: Climate change

Of all the threats to forests, climate change is the most insidious

Its impacts will be felt, to varying degrees, in many forests and woodlands around the world.

The Intergovernmental Panel on Climate Change (IPCC) estimates that at least one-third of the world’s remaining forests may be adversely affected by changing climate, especially in the boreal zone where the warming will be greatest.

Key forest types that are experiencing the most immediate adverse impacts are boreal, tropical montane, coastal and mangrove forests.

The situation
The increase in greenhouse gases is attributed mostly to human activities. Consumption of fossil energy is driving this trend, accounting for about three quarters of human-caused carbon dioxide emissions. Land disturbance and other sources – burning, loss, and degradation of forests, rangeland and soils – accounts approximately for the remaining quarter.

How climate change impacts forests
The effects of climate change, including increasing mean and peak temperatures and increase in number and intensity of droughts, affect forests around the world and the animals (including humans) and plants that depend upon them.

Research shows that climate change makes forests drier, suggesting that it is very likely forest fires will increase in number and severity due to increases in temperature and lower humidity.

No time to adapt
Because trees grow slowly, forests need time to adapt to environmental changes, but the expected rate of global warming and sea-level rise will mean that many forest types will not be able to keep up. Furthermore, in regions with high human populations, land for new forests to colonize may simply not be available.

In focus

Mediterranean and tropical montane cloud forests

In the Mediterranean, summers have become hotter, with less and less humidity and more winds. These create ideal conditions for forest fires. There are also more intensive rains and storms during winter which leads to increased vegetation – which in summer dries out and becomes fuel for fires.

Observations suggest that tropical montane cloud forests are also highly at risk due to fewer, higher clouds and warmer temperatures, with serious impacts already underway.

Wildlife cornered
Fauna is most likely to be affected through the change of habitat and the lack of water. As average temperature increases, optimum habitat for many species will move to higher elevations or higher latitudes. Where there is no higher ground or where changes are taking place too quickly for ecosystems and species to adjust, local losses or global extinctions will occur. Migration patterns of insects and animals are also reported to be shifting.

How forests impact climate change
When forests are lost or degraded, their carbon is released into the atmosphere in the form of carbon dioxide, the most important greenhouse gas. By continuing to lose forests, we contribute to climate change.

Future El Niño events - the periodic upwellings of warm waters in the Pacific Ocean which affect weather patterns across the globe - could increase incidences of fire, particularly in the forests of South America, releasing millions of tonnes of stored carbon dioxide into the atmosphere.