1. What is climate change?
Climate change has been known to the scientific community for at least 150 years. Irish physicist John Tyndall speculated in 1861 that water vapour and certain other gases can create a greenhouse effect in the atmosphere. The reason is that solar radiation powers the Earth’s climate system. Part of this radiation is reflected back, but some is absorbed and stays within the earth’s climate system.
Greenhouse gases (GHGs) absorb infrared radiation. Burning fossil fuels or releasing methane from the ground increases the relative concentrations of GHGs in the atmosphere, and means that extra heat is captured in the Earth’s climate system.
A short introductory subtitled video to the topic, prepared by the U.S. EPA, can be found here:
Humans have been burning fossil fuels steadily since the invention of the first widely used steam engine by Thomas Newcomen in the 1700s.
The figure on the left presents concentrations of the three main greenhouse gases (CO2, CH4, N2O) in the atmosphere. These have been rising steadily since the 1800s, primarily due to industrial use of coal. Emissions rose very sharply during the last 60-80 years due to exponential growth of the global population along with its dependence on ‘oil, gas and coal powered’ energy and transport systems. The graph show 1,000-year records of southern hemisphere background concentrations of CO2 in parts per million (ppm) in orange, N2O parts per billion (ppb) in blue and CH4 (ppb) in green. Levels shown were measured at Cape Grim in Tasmania and in air extracted from Antarctic ice and near surface levels of ice.
GHG emissions caused by humans, are directly responsible for the warming the planet has experienced so far.
See a video from NASA on this here: https://www.youtube.com/watch?v=-gHUHoqBn-Y
In 2015, average global temperatures reached almost 1°C above the pre-industrial average (1850-1900 reference period) for the first time.
According to leading scientists forming part of the Intergovernmental Panel on Climate Change (IPCC), the world should limit global warming to no more than 2°C above to pre-industrial levels to avoid severe consequences for the planet and for humanity. To reach this goal, global greenhouse gas (GHG) emissions need to be reduced by 40-70% by 2050 and the world would need to transition to a zero-carbon world by the end of the century.