The dire Reality of the Climate Crisis

Hanno Böck


CO2 emissions 1990-today

CO2 Emissions (Fossil fuels and Industry, GtC/yr), Global Carbon Budget 2019

I call this the chart of epic climate failure

CO2 emissions and economics

CO2 Emissions (Fossil fuels and Industry), Global Carbon Budget 2019

CO2 emissions and policy

CO2 Emissions (Fossil fuels and Industry), Global Carbon Budget 2019

So where are we?

The world is around 1 degree warmer and we are increasingly seeing effects

Heatwave in Europe (June/July)

Heatwave Europe

ESA, CC by-sa 2.0

Bushfires and heat records in Australia

Australia Bushfires

ESA, CC by-sa 2.5


Paris Agreement (2015)

All nations in the world agreed to 3 degree of global heating

That is probably not the story you heard about the Paris Agreement

Nations agreed to the goal of limiting global temperature rise to "well below 2°C"

"pursuing efforts to limit the temperature increase to 1.5 °C"

But they have no plan how to get there

In the Paris Agreement nations commit to so-called Nationally Determined Contributions (NDCs), which are, in effect, voluntary actions

[...] even if all unconditional Nationally Determined Contributions (NDCs) under the Paris Agreement are implemented, we are still on course for a 3.2°C temperature rise

UN Environmental Programme Emissions Gap Report 2019

Temperature Rise

Current (~)1 °C
Paris goal (ambitious)1.5 °C
Paris goal (minimum)2 °C
Paris NDCs3 °C
Current policy3-4 °C (or more)

The Science and the IPCC

The IPCC summarizes results from climate science


2018 the IPCC published a special report on 1.5 degree warming

It had two main messages:

  • There is a substantial difference between 1.5 and 2 degree warming
  • 1.5 degree is still doable

1.5°C or 2°C

Coral Reef

Coral Reef

Jim E Maragos, U.S. Fish and Wildlife Service, public domain

Coral bleaching

Elapied, Wikimedia Commons, CC by-sa 2.0

How many coral reefs will be destroyed?


Summers with an ice-free Arctic 10x more likely

1.5°Cevery 10 years
2.0°Cevery 100 years

Sea level rise by 2100

1.5°C0.40 meters
2.0°C0.46 meters

Population affected by extreme heat

Remember: Currently 3°C is much more plausible than 2°C/1.5°C

What is needed for 1.5°C?

Around 50% reduction til 2030, carbon neutral by 2050

Is the IPCC telling the full story?

A lot of scientists are worried that the IPCC is overly conservative

[...] the available evidence suggests that scientists have in fact been conservative in their projections of the impacts of climate change. [...] We suggest, therefore, that scientists are biased not toward alarmism but rather the reverse: toward cautious estimates, where we define caution as erring on the side of less rather than more alarming predictions.

Climate change prediction: Erring on the side of least drama? (Brysse, Oreskes, O'Reilly, Oppenheimer 2013)

We find that climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers.

Evaluating the performance of past climate model projections, Geophysical Research Letters, Hausfather et al

Are you confused?

Climate scientists have underestimated climate impacts, yet their models have been surprisingly accurate.

Can that both be true?

Actually yes.

Global mean temperature predictions have been very accurate, however predictions on specific effects of climate change have underestimated outcomes.

Did scientists get climate change wrong? (Sabine Hossenfelder interviews Tim Palmer)

Climate scientists are saying we need to act fast to avoid the worst outcomes of the climate crisis, but we can still do it

They have been saying similar things many years ago

The science did not get more optimistic

How is that possible?

Negative Emissions

All 1.5°C scenarios and most 2°C scenarios assume negative emissions in the future

Plant trees


Dr. Hans-Peter Ende, Wikimedia Commons, Public Domain

Planting trees is good, but it has limits and competes with other uses of land

We need to talk about Carbon Capture and Storage (CCS)

Storing carbon dioxide underground

CCS first entered the discussion in the context of new coal power plants, but it has largely been a failure

Today there are only a few CCS projects operating, most of them in the context of Enhanced Oil Recovery

Bio energy and CCS (BECCS)

Use bio energy and capture the emissions

Obviously it comes with all the problems that usually come with bio energy

Direct Air Capture

Directly removing carbon dioxide from the air

These machines will require lots of energy and it is questionable how fast this can be scaled up

Optimistic IPCC scenarios rely on technology that largely does not exist

Even if the technology works: How do you make that work politically and economically?

Feedback Loops and Tipping Points

Probably the most relevant criticism of the IPCC is that they have insufficiently considered the risks of tipping points and feedback loops

When warming causes more warming

Ice is bright, Water is dark


mary15, ABSFreePic, CC0

Albedo Feedback Loop

Ice reflects part of the sun's energy back.

When the ice melts less energy is reflected, the oceans heat up more.

Tipping Point

At some point systems may collapse independent of further warming

It is estimated that the West Antarctic Ice Shield is already collapsing, which will alone increase sea level by 1-3 meters in the long run

Risk of a Cascade of Feedback Loops

Hothouse earth study

The "Hothouse Earth" study warns that even with 2°C warming such a scenario can plausibly happen

Trajectories of the Earth System in the Anthropocene, many authors, 2018

There is significant uncertainty around feedback loops

These are long-term effects, some of them expected to unfold over thousands of years

What needs to happen?

We need to stop burning fossil fuels, that much is obvious

We need to get rid of this

Jänschwalde open cast mine

Hanno, CC0

Building renewable energy is easier than what most people predicted

Solar energy

Roy Bury, Wikimedia Commons, CC0

Solar graph Hoekstra

Auke Hoekstra on Twitter

Step 1: Switch to carbon-free electricity

Step 2: Electrify everything

electricity generation sources


How much electricity do we need?

  • 26 PWh/y: current world production of electricity
  • 160 PWh/y: total world energy production
  • 18-32 PWh/y: Petrochemical industry with CCU
  • 43 PWh/y: DAC for negative emissions

Kätelhön et al 2019

IPCC 2018

Where should all that electricity come from?

It's not just energy

Cement plant Berlin

Hanno, CC0

Do you know how cement is made?

CaCO3 = CaO + CO2

That is around 5 % of worldwide carbon dioxide emissions

Cow, Petr Kratochvil, CC0

Livestock is responsible for around 15 percent of greenhouse gas emissions

Is this a solution?

Impossible Burger

Sarah Stierch, CC by 4.0

There are solutions, but this is not going to be easy


Can we do something to counteract the warming from the greenhouse effect?

Solar Radiation Management

The most plausible idea is putting aerosols into the atmosphere

(This is reasonably well understood, as volcanoes do this)

This is not widely discussed yet and the IPCC explicitly excludes solar radiation management from its scenarios

Under normal circumstances considering to blast chemicals into the atmosphere sounds really crazy

If we end up in a situation where it is either this or a planet largely uninhabitable we probably need to have that discussion

Some people may think Geoengineering is an easy way out and a reason to avoid reducing emissions

There are a lot of wrong ideas about the climate problem

In a survey asking Germans what they think are effective actions to reduce personal CO2 emissions showed they have no clue

AT Kearney, 2019

Excessively overestimated impact: avoiding plastic bags, regional food

Excessively underestimated impact: eating meat

Efficiency is a Lie

People tend to think:

If we have more efficient technology this leads to less energy use and less emissions

This is not what is usually happening

VW Golf VW Tiguan

Guillaume Vachey, CC0

A VW Tiguan is twice as heavy as an original VW Golf and needs roughly the same amount of fuel

That is an absolutely amazing increase in efficiency!

It's just not helping the climate

Lufthansa not decoupling

Lufthansa Sustainability Report Balance 2019

Jevons Paradox

Rebound Effect

Efficiency does not automatically reduces emissions and may even increase them

A lot of the climate debate circles around having better technologies to solve this problem

There is nothing wrong with using technology, but it is simply not plausible that technical innovation alone will have any meaningful impact

The situation is dire

There is sometimes a thin line between saying how bad it is and making unsubstantiated claims

The Uninhabitable Earth Screenshot

New York Magazine / David Wallace-Wells: The Uninhabitable Earth

This article was largely based on a scenario called

RCP 8.5

RCP 8.5 is the worst case climate scenarios in the 2013 IPCC report

It is sometimes referred to as "business-as-usual" scenario

This scenario assumes humanity will use 6-7 times as much coal in 2100 compared to today

This is not impossible, but it looks rather unlikely given the growth of renewables

Discussions about implausible scenarios and RCP 8.5 led to a calculation based on IEA predictions, which estimates 3 °C warming by 2100, but with a significant uncertainty range (1.9 - 4.4 °C)

Breakthrough Institute: A 3C World Is Now “Business as Usual”

While some of the extreme scenarios look rather unlikely, the upper end of a plausible business-as-usual scenario is still catastrophic and 2100 scenarios don't consider long-term effects

There is growing agreement between economists and scientists that the tail risks are material and the risk of catastrophic and irreversible disaster is rising, implying potentially infinite costs of unmitigated climate change, including, in the extreme, human extinction (see, e.g., Weitzman 2009). (IMF)

Macroeconomic and Financial Policies for Climate Change Mitigation: A Review of the Literature (International Monetary Fund, Sept 2019)

On Modeling and Interpreting the Economics of Catastrophic Climate Change

Weitzman, 2009

I do not want to dismiss extreme scenarios, but often when I try to get to the sources of such claims not much comes up

Guy Mcpherson

Raquel Baranow, Wikimedia Commons, CC by-sa 4.0

Guy Mcpherson thinks climate change will kill all humans within the next decade and there is nothing we can do about it

This is not supported by the science

Arctic News

Arctic News is a blog written by a person with the pseudonym Sam Carana

Diagram of Doom / Arctic News

Sam Carana is more optimistic than Guy Mcpherson, he has a plan to stop it

Climate Plan / Arctic News

Methane Clathrate Bomb

Methane Clathrate or Hydrate is frozen methane on the ocean floor

The Methane Clathrate Bomb hypothesis is the idea that these deposits could rapidly melt and evade into the atmosphere

There have been a few scientific publications on this, but mostly scientists think this is impossible

To be clear: Methane Clathrates are a real concern and one of the feedback mechanisms in the climate system, but they are a long-term concern

These doomsday predictions tend to be a mixture of taking extremely speculative research and painting it as definite, massively overstating certain effects and confusing long-term with short-term effects

There are many cranks on the Internet and you can brush this off as ridiculous, but this stuff is creeping into the mainstream

Deep Adaption

Jem Bendell: Deep Adaption

Deep Adaption

VICE/Zing Tsjeng: The Climate Change Paper So Depressing It's Sending People to Therapy

This paper was rejected by a scientific publication due to its poor quality

It is heavily citing the questionable theories we just talked about, one of its main conclusions is based on references to the Arctic News blog

What if We Stopped Pretending Screenshot

Jonathan Franzen, New Yorker: What If We Stopped Pretending?

Our atmosphere and oceans can absorb only so much heat before climate change, intensified by various feedback loops, spins completely out of control. The consensus among scientists and policy-makers is that we’ll pass this point of no return if the global mean temperature rises by more than two degrees Celsius. Jonathan Franzen

That is not true

Some scientists think this could happen with 2 °C warming (e.g. the "Hothouse earth" study), but that is very different from a consensus

These doomsday predictions are not only problematic because they are wrong

"It is too late to do anything about it!"

Two very different claims, same conclusion

Climate change is a hoax / not caused by humans / not so bad Climate change will inevitably lead to doom
No change is needed

Climate change is not binary

We cannot avoid climate change - it is already here

But there is almost no scenario in which reducing emissions as fast as possible is not improving the situation

There is the idea that there may be a point of no return, a point where tipping points and feedback loops kick in and warming will increase on its own

Remember many of these feedback effects will happen over a very long time, particularly the melting of Antarctica and Greenland

Imagine a scenario where humanity needs to evacuate large areas due to heat and sea level rise

Or imagine having to deploy geoengineering technologies or massive numbers of air capture devices for negative emissions

Think about doing this over decades, centuries or millennia and wonder what is easier


The situation is really bad

It absolutely matters what we do about it

Ask yourself what you can do to stop this in 2020

Garzweiler coal mine