Climate Change
Global warming refers to the observed increase in our Earth’s average temperature. Although our planet experiences natural climatic variations, data shows that since records began the Earth’s global mean surface temperature has warmed between 0.95 and 1.20°C compared to pre-industrial level.
In its Sixth Assessment Report (AR6), the Intergovernmental Panel on Climate Change (IPCC) stated that over the past century, the earth’s average surface temperature has risen by approximately 1°C (likely between 0.8°C and 1.2°C) above pre-industrial levels. The National Oceanic and Atmospheric Administration (NOAA) state that 2022 ranked as the hottest year on record for the planet, knocking 2016 off the top spot and pushing 2019 into third.
An increase in the Earth’s average surface temperature alters the climatic system which affects weather patterns all across the globe. In July 2013, the World Meteorological Organization (WMO) announced that due to increasing temperatures and changing climatic patterns, more intense, extreme and unprecedented weather events are occurring every year. Unprecedented weather extremes are now in every region and on every continent and 2021 marked the highest number of extreme weather events in one year.
Further, records show that sea level is rising consistently with global warming. Melting ice sheets andglaciers along with the expansion of the ocean as it warms, have led to a global mean sea level rise of 20cm between 1901 and 2018. More importantly however, it is the speed at which sea level rise is accelerating which is a serious concern. The IPCC states that global average sea level rose by approximately 1.9mm per year between 1971 and 2006 but more recently has risen by 3.7mm per year between 2006 and 2018.
One of the primary causes of global warming is the enhanced greenhouse gas effect. The greenhouse gas effect is a vital and natural phenomenon by which greenhouses gases (e.g carbon dioxide, water vapour, nitrous oxide and methane) trap thermal energy from the sun in the earth’s atmosphere to keep it warm. This is referred to as the ‘greenhouse gas effect’, as illustrated in the image above.
Although the greenhouse gas effect is a natural and vital process, when too many gases are released in to the atmosphere, too much heat is trapped. The vast majority of climate researchers agree that this is causing global warming.
Greenhouse gas (CO2, CH4 and N2O) atmospheric concentrations have all risen exponentially since pre-industrial times. The 2021 IPCC AR6 states that is it ‘unequivocal’ that human influence has warmed the atmosphere, ocean and land and that widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred. There are a variety of activities which release these greenhouse gases including burning fossil fuels, clearing forests, fertilizing crop, storing waste and raising livestock.
Although not the most potent, CO2 is the most significant of the greenhouse gases and is responsible for around two thirds of human induced global warming. Current atmospheric carbon concentrations are at 412.5 parts per million (ppm), setting a new record high, despite the economic slowdown due to the COVID-19 pandemic. The last time atmospheric CO2 levels were consistently at or above 400ppm was around four million years ago, known as the Pliocene Era, when the world was approximately 3°C warmer and sea levels were higher than today.
Unless collective global climate action is taken and greenhouse gas emissions are curbed, it is predicted based on pledges made at the UN Climate Change Conference UK 2021 (COP26), in Glasgow, that the world is still on track a global mean warming of 2.4°C by 2100.
