The International Governmental Panel on Climate Change published it’s 1435 page Report titled: Climate Change 2014, Mitigation of Climate Change. It was the Working Group III contribution to this fifth assessment Report. This Report is based on science, the study of the real world based on fact and truth, 1300 scientific experts performing and reviewing 1000s of studies and reams of scientific data. Here’s the conclusion of this Report:
‘Mitigation’, in the context of climate change, is a human intervention to reduce the sources or enhance the sinks of greenhouse gases (GHGs). Mitigation is necessary because Working Groups I and II of the Intergovernmental Panel on Climate Change (IPCC) have concluded that the consequences of unchecked climate change for humans and natural ecosystems are already apparent and increasing, and the dangers of irreversible damage are significant. While there are uncertainties, many scenarios lead to substantial climate impacts, including direct harms to human and ecological well‐being that exceed the ability of those systems to adapt fully. The planet as we know it is threatened. The energy supply sector is the largest contributor to global greenhouse gas emissions and therefore offers a multitude of options to reduce GHG emissions. But the stabilization of greenhouse gas concentrations at low levels requires a fundamental transformation of the energy supply system, including the long‐term phase‐out of unabated fossil fuel conversion technologies and their substitution by low‐GHG alternatives. As Renewable Energy penetrations increase, such issues are more challenging and must be carefully considered in energy supply planning and operations to ensure reliable energy supply, and may result in higher costs.
The International Panel on Climate Change issued a Special Report on Global Warming of 1.5 Degrees Celsius in October of 2018, summary below:
Limiting global warming to 1.5°C would require rapid, far-reaching and unprecedented changes in all aspects of society, the IPCC said in a new 2018 assessment. With clear benefits to people and natural ecosystems, limiting global warming to 1.5°C compared to 2°C could go hand in hand with ensuring a more sustainable world.
"One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes," said Panmao Zhai, Co-Chair of IPCC Working Group I.
The decisions we make today are critical in ensuring a safe and sustainable world for everyone, both now and in the future, said Debra Roberts, Co-Chair of IPCC Working Group II. “The next few years are probably the most important in our history,” she said. “It’s a line in the sand and what it says to our species is that this is the moment and we must act now,” Roberts continued, “This is the largest clarion bell from the science community and I hope it mobilizes people and dents the mood of complacency.”
Christiana Figueres, the former UN climate chief who led the historic Paris agreement of 2015, said: “There is nothing opaque about this new data. The illustrations of mounting impacts, the fast-approaching and irreversible tipping points are visceral versions of a future that no policy-maker could wish to usher in or be responsible for.”
The report finds that limiting global warming to 1.5°C would require “rapid and far-reaching” transitions in land, energy, industry, buildings, transport, and cities. Global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This means that any remaining emissions would need to be balanced by removing CO2 from the air. “Limiting warming to 1.5ºC is possible within the laws of chemistry and physics but doing so would require unprecedented changes,” said Jim Skea, Co-Chair of IPCC Working Group III.
Here is NASA’s perspective on Climate Change. All information below is from Global Climate Change – Vital Signs of the Planet at https://climate.nasa.gov/evidence, except the text in italic. Note that on the diagram below CO2 levels are now over 400 parts per million, up from a peaks of about 300 ppm over the last million years.