CO2 emissions by source
One thing you need to learn if you are interested in climate change is that all numbers are fuzzy, not because they are inaccurate, but because there are different ways to ask a single question.
About 90% of the CO2 we emit which is raising atmospheric levels comes from fossil fuels, which are easiest to divide into coal, petroleum and natural gas for a conversation like this.
The rest comes from deforestation, reduced soil health in agricultural lands, and increasing deserts.
,You can get somewhat different numbers if you ask about the natural carbon cycle.
For all of human history the atmosphere has been slowly changing from about 175 ppm to about 275 ppm CO2.
This is/was the end of the last cold spell in the ice age.
We are technically still in the ice age, although this is an extended peak interglacial period.
,Every year the atmosphere sees the highest level of CO2 in May, and the lowest level the following September or October.
The changes are due to all the growth and death of plants on land and in the ocean, but the driver of the changes seem to be Northern Hemisphere land-based plant growth.
This cycle has been around for hundreds of millions of years.
,The Ice Age changes are due to shifts in the Earthu2019s orbit and distance from the Sun known as the Milankovich cycles.
There is plenty to read about them online.
In the ice age, CO2 (and methane) in the atmosphere follows temperature change, and acts as a feedback to magnify the direct change in warming due to the Earth being a little closer to the sun.
,The sun also changes its heat output on an irregular cycle, which lasts between nine and fourteen years on average, but which can disappear for several cycles in a row.
,All of these factors affect plant growth, and that affects CO2.
But before humans, this all operated in a balanced system which took hundreds of thousands of years to shift much.
Since we started using fossil fuels we have raised atmospheric CO2 from about 275 ppm to about 417 ppm (May of this year).
Thatu2019s enough by itself to change the Earthu2019s temperature by more than one degree F.
But CO2 is the greenhouse gas which we are changing the most.
It is neither the only greenhouse gas, nor the one with the largest natural impact.
Water vapor has more impact than CO2, but raising CO2 is increasing the water vapor in the atmosphere.
,Thatu2019s a quick sketch of the situation.
In late 2017 the cost of utility scale wind and solar farms (about a half square mile, 50 MWu2019s and $50 million is a good lower limit for u201cutility scale.
u201d Although some smaller projects are being built they cost more per MWh of output.
This means that we can replace all the fossil fuels we use with renewable electricity.
Itu2019s a longer conversation than I want to type right now, but we can use renewable electricity to make hydrogen, and from that we can replace everything that we presently get from fossil fuels, and almost all of it for less money.
Search for u201cCarbon Engineeringu201d to get a sense of where we are going with this.
,Dying leaves and small plants will remain the largest source of CO2.
But the problem with climate change is not natural.
It is that we are taking carbon which was removed from the atmosphere over many millions of years, and putting it back into the atmosphere in a couple of centuries.
If we want to stop this, we have to do a lot of things.
But if we use renewable wind and solar and energy efficiency to end fossil fuel consumption, all the other things will work.
If we donu2019t, there is no point in doing the other things.
,Until late 2017 it was hard to point to a clear alternative to fossil fuels which made economic sense.
Today, not solving climate change costs more than solving it.
The only remaining question is whether we end fossil fuels as fast as possible, or something less than that.
Country with highest greenhouse gas emissions per capita
What country is the biggest emitter of greenhouse gas in the world?The following pie chart from Each Countrys Share of CO2 Emissions is quite helpful.
,As you can see, China has now easily overtaken the USA as the emitter of the most CO2 due to itu2019s economic growth.
Itu2019s probably a good thing that China also leads the world in production of renewable energy infrastructure, being the pragmatists that they are.
We would benefit if we copied their approach to transitioning away from hydrocarbon fuels instead of getting bogged down in political blame games and faction fighting.
,If you look at the breakdown in terms of a per capita basis, itu2019s very different with the top 3 being Saudi Arabia, Australia and the USA, in that order.
In this case China sits in 12th position.
Biggest carbon emitters companies
There have been several articles recently concerning what companies biggest carbon emitters.
A good one is found at: Just 100 companies responsible for 71% of global emissions, study says.
Biggest contributors to climate change by country
u201cWhich country is the biggest contributor to climate change?u201d,The nation that is most responsible for contemporary anthropogenic global warming and its resultant human-caused climate change is the United States of America, having contributed a quarter of total emissions.