What is Climate Change?
Climate change has been defined by the Intergovernmental Panel on Climate Change (IPCC) as a change in the state of the climate that can be identified (e.g. using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer (IPCC report 2018). This is recognised as a problem with global implications by the world's leading scientists.
For millions of years the Earth’s climate has changed gradually over time, but in a relatively short space of time - only a few hundred years - the effect of human activity has dramatically increased this rate of change.
Why the climate is changing
Scientists have known for over 100 years that adding more carbon dioxide (CO2) to the atmosphere causes a warming of the Earth's surface. But now that the effects are starting to be felt public demand is growing to reduce our CO2 emissions, along with other Greenhouse Gases.
Before the Industrial Revolution, the Earth’s atmosphere could be viewed as a closed system: natural processes would add and remove carbon dioxide to and from the atmosphere in a balanced cycle that has been maintained for millions of years. But since then, various human activities have tipped this natural balance out of 'sync' by adding more carbon dioxide than can be safely absorbed by the natural processes.
The extra Carbon Dioxide and other greenhouse gases (GHGs), including Methane and Nitrous Oxide, cause the Earth to warm, in what is known as the 'greenhouse effect'. These gases act just like a greenhouse because they reflect bands of the Sun’s radiation back towards the Earth’s surface that would otherwise radiate straight back out, therefore warming the Earth's surface.
The greenhouse effect: greenhouse gases trap heat in the atmosphere (Wikimedia)
Data from Hawaii (below) illustrates how concentrations of CO2 have risen since World War II as economic activity has rapidly expanded across the globe. No natural processes or effects have been found that can explain such a rapid rise in CO2concentrations.
Carbon dioxide in the atmosphere 1960 - 2010, showing upward trend (NOAA)
Anthropogenic activities are estimated to have caused approximately 1.0°C (in 2018) of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. IPCC suggests that global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. This pace of change in temperature is unmatched in history. And so worrying is this temperature jump, it has led scientists to warn of potentially irreversible changes in our climate if allowed to continue.
Increases in GHGs serve to trap more heat in the atmosphere, therefore reinforcing the greenhouse effect's warming pattern, which may cause further emissions (from forest fires for example) and thus an enhanced greenhouse effect. It’s a vicious cycle which will only get worse if something isn’t done.
Scientists generally agree that to avoid 'runaway' climate change we need to restrict temperature rise to 2°C or below by 2100.
How will it affect UK Farmers
Climate change is about more than global warming. As well as rising temperatures putting stress on farmland across the world, greater extremes of both hot and cold temperatures are expected. Climate change will also bring altered rainfall patterns, raised sea levels, acidic oceans, more storms and unexpected weather events. Such changes could have huge consequences for farmers, growers and all those reliant on the land for an income.
If nothing is done the UK is forecast to have shorter, wetter winters, less rainfall in the summer and more stormy and unusual weather events. This will test farmers and growers and require new ways of growing crops and livestock. You can read more about the expected localised changes in climate in the UK here.
Warmer and milder weather will allow new pests to establish themselves in the UK and change the flowering dates of flowers and plants. Loss of biodiversity and native species will have knock-on ecological effects for farmers and damaging invasive species are expected to multiply.
What can be done?
A major review into whether it makes economic sense to fight climate change concluded that allowing climate change to continue unabated would result in costs equivalent to 2% of the world's GDP. Conversely, taking immediate action to combat the worst outcomes of climate change would cost only 0.5% of GDP.
The good news is that steps can be taken to fight climate change. The most important is reducing and stopping altogether the emission of C02 and GHGs into the atmosphere.
Farmers and growers can have a big impact by reducing their emissions, and even help absorb emissions from the atmosphere.
The toolkit explores how farmers and growers can reduce emissions and help combat climate change, benefitting at the same time from lower costs and new business opportunities. See the Conversely, taking immediate action to combat the worst outcomes of climate change 'Your Farm' section for more information on how to get involved.