The Tipping Points of Climate Change — and Where We Stand | Johan Rockström | TED

the Earth system scientists and climate scientists are getting seriously nervous the planet is changing faster than we have expected we are despite years of raising the alarm now seeing that the planet is actually in a situation where we're underestimated risks abrupt changes are occurring in a way that is Way Beyond the realistic expectations in science 15 years back I introduced the planetary boundary framework the scientific framework with the nine earth system processes that determines the stability the resilience and the life support on planet Earth 10 years back the world signed the Paris climate agreement almost 5 years back we entered the decisive decade where our choices will determine the future for all generations on planet Earth where are we on this journey halfway into this decade I will give you a scientific state of the planet report the most objective assessment that science can give today and it starts here we've reached 1. 2 de C of global mean surface temperature rise the warmest temperature on Earth over the past 100,000 years we have just scratched on 1. 5° c as an annual mean in 2023 but what worries us most is this we are starting to see an acceleration of warming over the past 50 years 0.

18 de C per decade from 1970 to 2010 but then from 2014 onwards it abruptly jumps up to 0. 26 per decade and if we follow this path we will crash through 2° C within 20 years and hit 3° C by the year 2100 a disastrous outcome caused by us humans but it's not only carbon dioxide any parameter that matters for human well-being and our economies look the same here you have it linear change up to the 1950s we go into the great acceleration and this is what we're seeing across overc consumption of freshwater the six Max Extinction of species over uriy our freshwater systems with nitrogen phosphorus all of it undermining the stability of the planet as if this was not enough we are seeing that this is now causing impacts across the entire economy we're seeing bigger and bigger invoices being sent by the Earth system onto societies across the entire world in droughts floods heat waves disease patterns human reinforced storms scientifically attributed to human cause climate change 40° cus of life-threatening heat across all continents occurring in 2023 52° C hitting the over thousand who lost their lives at the Hajj pilgrimage in June in Mecca Three Times Higher climate change risks now attributed to our cause of climate change 2023 up to 12,000 deaths $200 billion US of cost just in the US up to 100 billion us this is seriously causing economic costs we have scientifically in the past shown that this could cost a few percent of global GDP of the climate impacts caused by us I can tell you that the latest scientific assessment is what you see on the screen here an 18% loss of GDP by 2050 if we now follow the current path this is equivalent to $38 trillion of loss per year in 2050 it's starting to hurt both in human social cost and in economic cost and this is happening at 1. 2 de C of global mean surface temperature rise and we're following a path that takes us to 2.

7 de C in only 70 years and we've had a 10,000 year period where our civilizations have developed where we've had an enormous privilege of a planet at 14° c plusus 0. 5° c that's the Hollow Scene since we left the last ice age and if you look 3 million years back we never exceeded 2 deg C that's the warmest temperature on Earth during the entire quaternary the coldest Point -5° ice AG I call this the corridor of life is it surprising that we scientists are getting really really nervous but it's more it's so much more than this the first issue is buffering capacity the second is the risk of Crossing tipping points and both are moving in the wrong direction buffering capacity is the Earth Systems ability to dampen shock and stress like for example soaking up greenhouse gases in intact nature on land and in the ocean and so far Mother Earth has been so forgiving here we have the evidence what you see here is the hocky Stick of fossil fuel burning in red and deforestation in yellow is it this tremendous climate forcing that has caused the 1. 2 de cus climate crisis so far the answer is no 53% of the carbon dioxide from fossil fuel burning and land system change have been soaked up by intact nature on land and in the ocean it's the only the blue sliver you see here which remains in the atmosphere causing the climate crisis so far the problem is we have more and more scientific evidence of cracks in this system let's start on land land absorbs 31% of the carbon dioxide from our greenos gas emissions we have more and more scientific evidence across so much research that the Boral forest in the Canada or the temperate mixed forest in Germany and Russia are starting to lose their carbon uptake capacity did you know that the latest science shows that the part of the Amazon rainforest planet Earth's richest biome on terrestrial land has already tipped over and is no longer a carbon sink it is today a carbon Source it's no longer helping us but as if that was not enough what really worries us today is the ocean the ocean absorbs 90% of the heat caused by human induced climate change this is well understood but what really worries us is what you see here this is the latest data on sea surface temperature across the ocean what you see here is from 1980 until today how gradually the ocean surface just get warmer and warmer it's actually warming all the way down to 2,000 M depth this is well understood in science it's a deep concern it's well represented in the climate models we understand it then suddenly in 2023 something happens temperatures just go completely off the charts 0.

4 de C outside of the warmest temperature in previous years what's happening we admittedly must be honest here we do not know El Nino is certainly partly to blame but cannot explain at all 2024 it just continues what is happening we do not know but the candidate number one is the energy imbalance caused by us humans in one year alone the heat equivalent to 300 times Global electricity use is absorbed in the earth system is it is it what we see on the screen here an ocean that is starting to lose resilience an ocean that is at risk of releasing heat to the atmosphere and self-amplifying warming we do not know but one thing is for certain the ocean is sounding the alarm reasons for concern yes we are now at a point where are forced to ask the following question are we at risk of pushing the planet out of the Basin of Attraction the stability of the planet where we've been since we left the last ice age the extraordinarily stable Holocene State and if we pushed ourselves outside drifting away unstoppably towards a hot house Earth where we get self-amplified warming and losing life support on Earth what could take us there well we know it it is if we cross tipping points big systems like the green and ice sheet the overturning of heat in the North Atlantic the core Reef systems the Amazon rainforest are tipping elements systems push them too far and they will flip over from a desired state that helps us to a state that will self- amplify in the wrong direction going from Cooling and dampening to self-amplifying and warming a rainforce tips over to a savan state now we have now mapped the 16 tipping element systems we are now scientifically Catal that regulate the climate system these 16 and you see the five in the ground zero on planet Earth in the Arctic are connected via Cascades through the ocean particularly via the amok the Atlantic overturning of heat in the ocean all the way down to Antarctica these are Big biophysical systems that we all depend on Global Commons for the stability of the planet the question is at what temperatures are they at risk of tipping from helping us to becoming self-amplified foes well for the first time we have an attempt to answer that question what you see here are the 16 tipping element systems on the y- AIS and in red you see the uncertainty range the best estimates in science darker the red the higher the risk of tipping is the temperature levels at which they're likely to cross their thresholds the average temperature at which they are likely to tip is the yellow circle lines you see here what this tells us is the following five of these 16 are likely to cross their tipping points already at 1. 5° C the green ice sheet the West Antarctic ice sheet abrupt thawing of Perma Frost losing all tropical cor Reef systems and collapse of the Barron sea ice justed two ice sheets hold 10 m sea level rise which would be unstoppable on the long term now sure there's scientific uncertainty here as you see from this graph but there's one red thread in science for Humanity in the scientific message and it's this the more we understand of the your system the higher is the risk and here is the proof this is five ipcc assessments the intergovernmental panel on climate change 30 years of scientific advancements here again you see risk assessment darker the red higher the likelihood of causing irreversible change in the climate system 30 years back the risk was put at 5° C of tipping and coming down to current state of science the risk is set at 1. 5 to 2° C we are in the midst of a danger zone today but it can be even worse than that let's go to the Amazon basin again the richest terrestrial ecosystem on land climate science estimates the risk of the Amazon rainfor is tipping over irreversibly to a savannah at 3 to 5° of global mean surface temperature rise a really high temperature you know unlikely even to be met over the next 70 years but if we lose Forest cover the risk is that the system can tip already at 1.

5 to 2° C if we lose more than 20 to 25% of forest cover so that's a very dangerous combination where are we today we are at 1. 2 de cus Global mean surface temperature rise and 177% of deforestation we are very close to a Tipping Point in the Amazon rainforest very close what shall we do to avoid these unmanageable outcomes well the ipcc is clear on the pathway to stay under 1. 5° C to avoid Crossing tipping points we need to operate to navigate within the global carbon budget that gives us a chance of holding 1.

5 what remains for us is only 200 billion tons of carbon dioxide that we can continue emitting to have a 50% chance of holding 1. 5 we emit today 40 billion tons of carbon dioxide per year giving us 5 years at current rate of emission before we've consumed the budget we are seriously running out of time and the pathway for a safe landing is also well studied and understood you have it here bend the curve of emissions immediately and follow a path where we reduce emissions by at least 7% per year for a safe landing and a net zero World economy by 2050 but it's more than that we also know that even if we succeed with this we have already loaded the atmosphere with so much greenos gases with so much climate forcing that we inevitably face a period of overshoot we must now be prepared for a very likely breaching of the 1. 5° cus planetary boundary on climate somewhere between 2030 and 2035 in 5 to 10 years time and then have at best a 30 40 year period of overshoot before we can come back to 1.

5 by the end of this Century we would exceed with 0. 1 to 0. 3 de C the 1.

5 limit meaning up to 1. 8 de c what does this tell us well I can tell you there are two main messages message one buckle up we know for certain 100% certainty that this means more droughts more floods more heat waves more human reinforce storms more disease during one generation's time 2023 the warmest year on record will be looked back upon as a mild year message two why would the planet come back to 1. 5 after overshoot well the answer is very simple the health of the planet must be kept intact we must continue having a planet that can absorb 50% of the carbon dioxide we must have a planet that crosses no tipping points we must have a planet that remains healthy and keeping heat intact in the ocean that is why we need planetary boundaries the planetary boundary framework that defines the nine earth system processes that regulates the stability and resilience of the entire planet climate biodiversity nitrogen phosphorus land fresh waterer air pollutants and chemicals that is the challenge to summarize that there is no 1.