What is global warming?
The term global warming reflects the fact that the mean annual average temperature of the Earth’s surface has been increasing for many decades. The planet is getting warmer because of atmospheric greenhouse gas emissions from fossil fuels, like coal and natural gas. According to NASA, the global mean surface temperature is almost 1C warmer now than in 1880.
Although the average temperature changes seem modest, they vary considerably. The biggest changes are at higher latitudes. These affect atmospheric and oceanic currents and the extent of sea ice, which together change the climate.
Climate change poses a major threat to our natural environment, both directly and indirectly:
- The weather is becoming more unpredictable with more frequent and severe events such as storms, droughts and flooding.
- Sea ice is declining at almost 13% each decade, causing sea levels to rise at a rate of 3.4mm every year.
- Coral reefs are experiencing bleaching events and die-off, threatening the marine ecosystems that depend on them.
- Melting permafrost is releasing methane, a powerful greenhouse gas, creating a feedback loop that could result in runaway global warming.
What are the effects of global warming in the UK?
The Met Office's UK climate projections suggest that all areas will be warmer by the 2080s, with summers warming more than winters.
Rainfall patterns will change, with more winter precipitation (less likely to fall as snow) in the west and less summer rain generally.
The UK will also experience extreme weather events more often, such as droughts and severe storms.
The impact to wildlife of changing seasons
The impact of these climate events will stress our native wildlife further, interfering with natural cycles that have helped shape our living environment.
The extended cold periods we usually experience in winter normally present a life-or-death challenge to many species. But this helps keep nature in balance. Warmer winters allow greater survival rates. This can place pressure on host food sources in supporting larger populations the following spring.
Non-native species arriving in the UK will have a better chance to take hold. They often lack natural predators, so have the potential to survive, persist and even thrive - becoming invasive. Examples of invasive species include Himalayan balsam, the harlequin ladybird and the ring-necked parakeet.
Worryingly, many pests and diseases of our native trees will be more likely to survive winter and become established.
How will global warming affect woods and trees?
A changing climate will inevitably impact the factors that control germination. These changes are already creating mismatches in nature.
For example, the earlier arrival of spring leads to earlier leafing dates for many trees. This in turn means that peak numbers of leaf-eating caterpillars also occur earlier. This can lead to a shortage of supply for birds such as blue tit, great tit and pied flycatcher, which don’t seem to be changing their egg laying dates to match.
Patterns like this could lead to changes in the composition of our woodland species and alter their distributions across the landscape.