As much as we may hate going back to the basics of things we think we (kind of) understand, the revisit almost always uncovers things we didn’t know, we don’t know1.
To understand climate change, let’s first revisit ‘climate’ in brief.
Weather patterns, averaged for at least 30 years, constitute a region’s climate. These patterns, in turn, are a culmination of a complex interdependent system of air, water, ice, land and life. One messes up, the others get a jolt.
The perfect representation doesn’t exis…
While weather patterns have a day-to-day dynamism, climate, being an average, is not as dynamic. Climate change is felt over hundreds or thousands of years - remember reading about the Ice Ages in middle school?
If climate change has been happening all through the history of our planet, why fuss over it now?
The hypothesis and the science
The Industrial Revolution of the 19th century which mechanized humanity’s progress did so at the cost of the environment. The steam engine happened and thereby began a fossil-fuel-guzzling spree which led to reckless emission of greenhouse gases (GHGs)2. Now, the greenhouse effect (when atmospheric GHGs trap the reflected solar heat) is a boon to our existence since it is responsible for making the Earth about 35℃ warmer than it would be if there was no atmosphere. However, human activity3 has been shoving BILLIONS of tonnes of carbon dioxide in the air (along with other GHGs), resulting in an accelerated heating of the planet owing to this effect.
Now, visualize 107 million tonnes CO2 being added to the atmosphere EVERYDAY.
Coming back to the interdependent system we saw above, think of it as a group of friends. In this group, one friend keeps sharing exciting ‘strictly confidential’ secrets with her closest mate, which the latter responsibly keeps to herself…ONLY till her max capacity (read excitement control) is breached and a Chinese whisper of “Don’t tell this to anyone…” begins with the rest of the group. The air, oceans, soil and plants have huge CO2 absorption capacities (‘carbon sinks’) but the amounts being emitted are far more than the natural processes can remove from the atmosphere.
The following visual highlights this fact through five different scenarios of CO2 emission levels (in increasing order) taking into account the past, present and future emissions -
Fun fact: During the historical period (1850–2019), the observed land and ocean sink took up 1430 Gt4 CO2, i.e. 59% of the emissions
The validation
Global surface temperature in 2001–2020 was ~0.99°C higher than in 1850–1900 (~80% due to CO2). This means we’re already a degree Celsius hotter than pre-industrial levels.
Temperature increase during 1970-2020 has been much faster than in any other 50-year period over at least the last 2000 years.
Global average sea level increased by a little less than 1 foot (same as the height of an infant) between 1901 and 2018.5
The annual increment in atmospheric CO2 over the past 60 years is ~100x faster than previous natural increases, such as those that occurred at the end of the last ice age (11k - 17k years ago).
The ocean has absorbed enough carbon dioxide to become 30% more acidic and consequently, adversely affect marine life.6
In the given context, “parts per million” refers to the number of carbon dioxide molecules per million molecules of dry air.
Summary
This climate change, unlike the previous ones, is NOT NATURAL but human-induced.
So, climate change = global warming?
No.
Global warming is a subset of climate change.
Global warming refers to the increase in the surface temperature — first-order effect of the greenhouse effect.
Climate change, however, is all-encompassing as it takes into account all the changes in the complex interdependent system that we identified above — first-order and ripple effects of the greenhouse effect. The melting polar caps, receding glaciers, increasing sea levels, acidification of oceans, frequent floods, forest fires, intense droughts & heat waves, oscillating frequency and intensity of precipitation…together constitute climate change.
Is a 1°C or 2°C change in temperature even worth the discussion?
It’s intuitive to think of this change in temperature as simply a local change. However, the reality is that this increase is an average for the overall change in Earth’s temperature, which means that the change will not be uniform, rather a messy collective of extreme events. So messy that it has bred community-level injustice and fancied the interest of geopolitics (more on this in a later post).
An increase of as (seemingly) less as 0.5°C, has been examined to create a turbulent butterfly effect resulting in more frequent and intense tropical cyclones, heatwaves, precipitation and droughts. The Arctic is expected to be practically ‘sea ice’-free at least once before 2050.
Each of these extreme events further have a localized domino effect which ultimately releases more GHGs and also affects survival of lifeforms.
It’s a flywheel.
Where are we now and who’s accountable?
In 2015, the world converged, on paper, to do something about climate change whereby all of them signed a legally binding international treaty, The Paris Agreement. The consensual goal is to keep the increase in global average temperature within 2°C above pre-industrial levels while making a concerted effort to limit the increase to 1.5°C above pre-industrial levels. In short, aim for <=+1.5°C but definitely achieve <+2°C.
As part of this agreement, countries have been submitting their Nationally Determined Contributions (NDCs), a quantified public commitment to reducing / negating emissions. While India has committed to achieving net-zero emissions (active emissions = emissions removed from the atmosphere) by 2070, USA has committed to reaching net-zero by 2050.
Realistic deadline to achieve the <=+1.5°C scenario at current emission levels:
Current annual emissions: ~41 Gt
CO2 and CO2e emissions budget remaining: <360 Gt
Years remaining: 8 !!
Let’s get closer to reality…
Trying to figure, where’s the ‘Remaining’ in the budget?
There isn’t.
This only means one thing - reducing emissions IS NOT enough, time to pull out legacy emissions from the atmosphere.
This pretty much explains why first principles’ thinking isn’t as common as we may otherwise expect it to be…both from others and ourselves
Major GHGs: water vapour, carbon dioxide, methane, nitrous oxide, ozone & fluorinated gases (from refrigerators, ACs, electronics, cleaning agents etc.)
Also referred to as ‘anthropogenic’ in climate science
1 Gt (gigatonne) = 1 billion tonnes
Source: https://www.climate.gov
That was an eye opener!
Good 'revisit' teaser. Looking forward to further deeper dives!