There is no doubt that enough scientific evidence has been collected to confirm that climate change is occurring and that it is largely caused by human activity, especially the production of greenhouse gases by the burning of fossil fuels.
These changes in the climate can result in significant negative effects on humans, animals, plants, and microorganisms. The changes involve rising sea levels, increases in intense rainfall events, decreases in sea ice cover, more intense heat waves, increases in wildfires, and ocean acidification..
There a number of reasons why predictions such as these include a measure of uncertainty, including:
- It is not known with certainty how human societies will produce and use energy and other resources in the years ahead.
- Some of the Earth’s ecosystems are not fully understood, for example, ice sheet dynamics and cloud processes.
- Events such as El Nino have a competing effect.
- Some climate change predictions have long time lags.
- There is a possibility of a tipping point being reached with some systems resulting in sudden changes taking place.
Despite any uncertainties that exist the changes listed above are definitely occurring. Several of these changes are of particular concern:
- Increasing levels of greenhouse gases in the atmosphere. Despite a few years of levelling off, the greenhouse gas emission from the burning of fossil fuels started to increase again in 2017. This was in part due to increasing fossil fuel usage in China and India.
- Increasing temperatures in high latitudes around the Arctic Ocean.
- Shrinking glaciers and smaller areas of sea ice. In 2017 the lowest sea ice winter maximum levels were recorded. The consequences are increasing sea levels.
- Increasing size and frequency of storms and hurricanes. As experienced on the East Coast of the USA in 2018.
- Increasing frequency and size of wildfires. As being experienced during the drought in California and other US states during 2018.
These comments attempt to sum up the general current thinking about climate change – from the scientific rather than a political viewpoint. In a later section we will look in more detail at the the conclusions of the 2018 IPCC Report Global Warming of 1.5ºC.