How does cutting emissions result in lower temperatures while there is still high amount of CO2 in the atmosphere?



In [this page]( it says “scientific consensus is temperature would remain constant or decline if emissions were suddenly cut to zero”. There are scenarios in page 74 of this [IPCC report]( We can see that in some scenarios CO2 levels are high but temperature remains same or declines. Also, we know that when we cut the emissions CO2 levels in the atmosphere will remain high for centuries. How do these projections work?

I thought earth was getting warmer because of the high levels of CO2 in our atmosphere. In the scenario that we cut emissions, there will still be high levels of CO2 in our atmosphere but many scientists says temperature won’t go up. What am I missing?

Edit: I believe I haven’t made my point clear. Of course CO2 levels [will start to decrease]( when we cut emissions. However, in the last century, temperature on earth’s atmosphere were increasing due to the greenhouse gases(ghg) in our atmosphere. And when we stop emitting these gases, we will still be having too much ghg in our atmosphere. They will **slowly** be captured by plants and ocean. However, the claim is that even with this high levels, [temperature will stop increasing]( What is the difference between having high ghg percentage on atmosphere while also emitting, and having high amount of ghg while not emitting?

In: Earth Science

CO2 is consumed by plants, we are producing more CO2 than could be consumed by our existing amount of plants. By reducing the emissions of CO2, we can allow our plant base to catch up. One element that always seems to be missed: cut emissions AND rejuvenate the ecosystem (stop clear cutting, replant forested areas etc.)

Plants on Earth absorb CO2 and produce O2. The reason CO2 levels are rising is because we’re producing more CO2 than all the plants on earth can covert it, but if we suddenly cut emissions, the plants can sort of “catch up”.

The Earth does have means of slowly reducing the amount of greenhouse gases in the atmosphere. Some decay naturally, while others get absorbed by plants and by water, and converted into new plant matter and rock, and dissolved in the ocean. If we cut emissions and prevented Earth reducing greenhouse gas levels, we’d still warm up, but it would be slower. However, if we could reduce emissions below the amount Earth absorbs, we’d slowly cool down.

Trees eat CO2, it also gets sequestered in the ocean and in a bunch of other things. Its like the water cycle but slower, there are processes for it to return to earth and come out of the atmosphere.

Its why a lot of nations are planting huge amounts of trees, precisely because we want to work on that side of it too

The environment will, on it’s own, gradually sequester CO2 in the atmosphere through various processes, thus the amount of CO2 in the atmosphere will come down on it’s own, albeit slowly.

If you only look at CO2 and incoming sunlight you reach a temperature equilibrium very quickly. CO2 reduces the rate of heat leave the earth, but if you look at the temperature over a day the temperature rises when the sun is up and drops when it is down, so change just from CO2 is one that is reached within days, I certainly occur in a year and I assume the temperature in the report changes in average temperature over a year.

So constant CO2 levels would result in a constant temperature. It I not the case that adding CO2 today has a direct effect that increases the temperature over decades.

There is also an indirect effect where the higher temperature changes the earth
An example is warmer winter result in less snow, less snow reflects away less light and it gets warmer. If the artic gets warmer organic matter that is today frozen starts to melt and you get CO2 and methane released from it.

So even if we do not release any more CO2 the temperature can rise because of how it changes Earth and it is the effect that can take decades. The CO2 level can also rise because of the change that happens on earth. CO2 can also drop as a planet and even animal can bind it and remove from the atmosphere. Coral and another sea animal with hard shells build it up from carbon and another element. It is a way an enormous amount of CO2 can be bound even if it can be a slow process.

All planets have their natural heating and cooling phases, affected/caused by solar radiation, internal processes, etc. On Earth, increased CO2 means plants grow faster and bigger, and cover more land. Reduced CO2 means plants grow slower and smaller. There is more surface area covered by forest today than any point in recorded history which is the planets natural way of balancing things.

You just need to be careful, these science deniers will keep spewing their “manmade” climate change crap, just as they have for the past 2 centuries or longer. CO2 is just their excuse for this planet. every 10-20 years they change from global warming to global cooling and back and forth. They saw the educated population knew they were full of crap so now they just use climate change as their excuse to steal more money while changing nothing.

The claim that as soon as we stop increasing CO2 emissions the temperature will also **immediatelly** stop increasing is false. It will help but the effect will take a while to appear.

You can simplify and think of the planet as a whole system that both receives energy from the sun and re-emits energy to space. The ammount of energy is in equilibrium for any given temperature. (This is a very naive aproximation)

In general having more CO2 makes the planet keep more of that sun energy because CO2 prevents it from being re-emited to space and hence temperatures increase, relative to the ammount of CO2 in the atmosphere. The thing is as the planet gets hotter it also increases the ammount of energy it emits to space up to the point that if the CO2 stops increasing, the temperature will also stop increasing, and remain constant (for a given ammount of CO2) because both absorbtion and emission are in equilibrium.

BUT, this asumes that the effect of the CO2 on global temperature is immediate, and this is not the case. The planet has what we call a temperature inertia in the form of the seas and landmass that generally require much more energy to change the temperature than the air. This is why the increase of the sea temperature is such a worrisome thing. In a sense the temperature will keep increasing until those “heatsinks” reach equilibrium consistent with the energy that the planet retains. They have yet to do so.

The really big danger is that there are huge ammounts of CO2 and methane trapped under ice both on land and on the ocean and as temperatures rise and that ice melts that CO2 and methane (wich is much stronger than CO2 at making the planet keep it’s energy) will escape and far outstrip the effect that humans have. This will cause temperatures to rise further and cause even more gasses to be released. Also, at higer temperatures all those processes that absorb CO2 (plants) will also start to become less and less effective. This is a doomsday scenario because there is nothing we can do to stop it, once it starts to really get going.