Climate change can have different terms surrounding the topic which mean different things, for example, climate change is defined as “a change in global or regional climate patterns” which does not necessarily mean an increase in temperatures. Global warming however just means an increase in the overall temperature of the earth's atmosphere caused by Greenhouse Gases (GHGs). This group of gases include: Carbon Dioxide, Carbon Monoxide, Methane, Water Vapour, and Chlorofluorocarbons, all absorb and emit energy within the thermal infrared spectrum, part of the greenhouse effect. The increase in GHGs means that more heat radiation is sent down from the atmosphere and more trapped within the atmosphere as this radiation can reflect off the atmosphere back onto the earth’s surface.
This is how eventually the globe will warm up and is proved historically over time that carbon dioxide and global temperatures have causation between each other, as rotations of ice ages in the past million years show the Carbon Dioxide increasing and decreasing respectively to the temperature after a short time gap.
With the science out of the way, in recent times climate change did not become a large issue on the global stage until the second half of the 20th century. The science behind climate change, however, were discovered in the early 19th century when it was first suggested that the climate had a natural driver to change it, with the greenhouse effect suggested by Joseph Fourier in 1824 then discovered subsequently over the century. This was argued to have some impact from humans in the late 19th century. Evidence for this gathered in the 20th century and a consensus was reached in the 1990s in which it was agreed that GHGs caused most climate changes (as some can be caused by the Milankovitch Cycle along with some natural disasters such as volcanoes).
The IPCC (Intergovernmental Panel on Climate Change) was formed in the 1990s. This board was formed to provide “an objective, scientific view of climate change” along with all impacts of resultant changes. The first major meeting on climate change of the UN was in 1995 in Berlin. It was known as COP 1, and we are currently on COP 25 in December 2019, which was going to be held in Brazil before Jair Bolsonaro was elected as president, so it was switched to Santiago in Chile, with COP 26 planned for Glasgow in 2020.
The first major events at these meetings were in Kyoto at COP 3, in which the Kyoto Protocol was adopted, with most industrialised nations agreeing to the legally binding reductions in greenhouse gas emissions. The USA was required to reduce it by an average of 7% below 1990 levels. This was not passed by the Clinton administration and was explicitly rejected by the Bush administration in 2001. This was brought into law in 2005 but academic sources have doubted the protocol's effectiveness. The Paris Agreement was the next major agreement for climate change deciding reductions of emissions from 2020. This agreement was negotiated to keep the increase in temperature to below 2 degrees centigrade above preindustrial levels and to pursue keeping it to a 1.5-degree increase.
This has had some criticism showing that even with a rise of 1.5 degrees there will still be irreversible damage to ecosystems and our current way of life, as highlighted in the IPCC report released in November 2018. It was also described as conservative in its impacts, given it did not even include about climate refugees summing up the current positions this report was only acknowledged as 4 countries: the USA, Russia, Saudi Arabia and Kuwait all prevented it from taking place.
Also over the past year, school climate strikes have been popularised across the globe, first by Greta Thunberg, and has had multiple strikes across the globe in 2019. In response, some governments have declared a “climate emergency”, including the UK, Ireland, France and Canada, with 1087 jurisdictions in 20 countries also declaring it. Even with this, it is still uncertain whether these nations will be able to prevent what the IPCC is warning against.