1°C warming is actually 2°C warming

Earth as a whole has warmed about 1°C since 1850-1900. And the goal of the Paris Agreement is to forestall 1.5°C or at least 2°C of warming. What is easy to overlook is that these numbers represent an average.

Oceans comprise 71% of earth’s surface and take longer to warm than land. They have indeed warmed about 1°C. Since 1979 land surface temperature – which affects us most directly – has risen about double that of ocean surface temperatures. According to NASA, since the year 2000, land temperature changes are 50% greater in the U.S. than ocean temperature changes; two to three times greater in Eurasia and three to four times greater in the (Ant)Arctic.

So when scientist discuss “preventing 2°C of global warming” they are really talking about forestalling around 3°C to 6°C warming on most land surfaces.

Figure: Warming in 2 RCP-scenario’s. Source: IPCC Climate Change 2014 Synthesis Report

The Arctic warms fastest; a phenomenon known as ‘Arctic amplification’ (see figure above). This is also supported by paleoclimatologic data: In the early Eocene (54-48mln years ago), while sea surface temperature at the tropics was about 6°C warmer, at the poles it was about 14°C warmer.

Different places and surfaces warming at different speed will have huge consequences. For example, the just mentioned reduction of the ‘Equator-to-pole surface temperature gradient’ (from e.g. 28°C now to 20°C), has been linked to changes in ocean circulation, behaviour of the jet stream, and the shifting of the Intertropical Convergence zone (ITCG) – determining a.o. Sahel rainfall, tropical storm activity and Californian drought.

Migrate northward or southward?

Where will you migrate to in the face of climate change? Will you go to a country in the Southern Hemisphere (> 45th parallel): New Zealand or Chile maybe? Or will you go to a country in the Northern Hemisphere (> 50th parallel): Canada, Russia or the Scandinavian countries? Which of the two will it be?

Earth’s land mass is mainly located in the Northern Hemisphere (67,3% of the total). Almost 40% of the Northern Hemisphere’s surface is land, against 19,1%  of the Southern Hemisphere (of which 5,5% is Antarctica).

Also, the main continents of the world are funnel-shaped. The further South you go, the less room there is. The 45th South Parallel passes for 97% through open ocean. The 60th  South Parallel does not ever hit land. More warming means that the habitable zones in the Southern hemisphere will get smaller. In the North there are – still – huge swaths of land.

Figure: Cumulative land mass by Latitude, source: andywoodruff.com

The Southern Hemisphere will warm less, because of a greater body of water and the Antarctic. The North is predicted to be up to 1.6°C warmer than the South on a Business As Usual emissions-trajectory. Also, the energy it costs to melt Antarctic ice sheets can, depending on how fast the West Antarctic ice sheet disintegrates,  delay future warming in cities such as Buenos Aires and Cape Town by 10-50 years.

Contraintuitively, the warmer North may be bad news for the South. Tropical rain bands tend to favor the warmer Hemisphere and may thus shift Northward, drying out parts of the Southern Hemisphere. At the same time, the behavior of the gulf stream and polar jet stream – and subsequent erratic weather patterns – in the Northern Hemisphere is still up for grabs.

More than 4°C warming? Homo homini lupus est

A premise of this website is that the earth will warm by approximately 4°C by the end of this century. But what if it will be more? The amount of possible feedback loops (permafrost thawing, boreal and tropical forests burning, et cetera), adjusted climate models, oceans that have absorbed more heat than previously thought and the ‘faster than expected’ mantra we keep hearing every week, make it ever more plausible that by the end of the century the earth will be spiraling up towards a ‘hothouse earth’.

So, where to migrate to then? The best advice is probably to get away from the masses. If things get really bad food will be scarce and people tend to turn on one another. The director of the Potsdam Institute for Climate Impact Research declared that at 4°C warming “It’s difficult to see how [the earth] could accommodate a billion people or even half of that.” In such or worse scenarios horde after horde of desperate people will plunder and try to hold any piece of viable land and the very limited resources that are left.

Canada and Russia are both massive and sparsely populated. A warmer climate might mean more agricultural possibilities in these countries. So moving there might offer the best chances for survival. Although, with no Arctic sea ice and a meandering (polar) jet stream, conditions might get worse even there.

Figure: The Guardian, may 2019.

Or, counterintuitively, go to a place where people will definitely not flock to. The Siberian and Inuit people still exist because other people were not interested in their land and scarce resources, while mainstream native Americans had to bear the full brunt of colonization. Would you rather struggle against nature or against your fellow man? As some users of the subreddit r/collapse suggest: “So go to a desert or to the Antarctic. Pick the most inhospitable place possible, were it’s not just hard to survive, but a life or death struggle even for the prepared. Congratulations, come collapse of civilization you will not have to worry about looters since they’ll never survive to get there. The environment will be your only foe and you will be well adjusted before and ready as can be before the rest collapses.

Drought-related migration in India

In June 2019 about 50% of India was grappling with water shortage, with between 300 and over 500 million people affected. The situation was especially dire in Maharashtra (~120 million people) and Karnataka (~70 million people). In Maharashtra alone, over 6,500 tankers were supplying water to many thousands of drought hit villages and hamlets. Extremely dry conditions followed deficient rainfall since 2015 and especially deficient monsoon rains in 2018 and 2019 (until June at least).

The drought has led to – mass – migration. The Guardian mentions an area in Maharasthra were up to 90% of the population has fled –  “village after village is deserted”. Reuters mentions “emptied out villages” in Bundelkhand where around 55% of the population had fled. Articles feature quotes such as “We got drinking water only once a week. Had I not left … my kids would have died.” India Today describes wells and hand pumps in villages zealously guarded by men wielding lathi (sticks) to prevent theft of water.

Figure. Emergency Response Coordination Centre (ERCC) – DG ECHO Daily Map | 28/06/2019

A governmental body (NITI Aayog) estimates that India’s  water demand by 2030 will be twice its available supply. Groundwater, the source of 40% of India’s water needs, is depleting at an unsustainable rate. The water resources ministry warns that some 21 cities , including Delhi, Bangalore and Hyderabad, could all run out of groundwater as early as next year. This year already, Chennai’s (India’s 6th largest city – 10 million inhabitants) 4 reservoirs ran dry. Among the measures taken or announced was a daily 220 kilometer daily water train to bring in water.

Deforestation, urbanization and lacking water resource management are putting huge pressures on water reservoirs. Although most climate models predict more intense monsoons due to climate change, weather data collected in the region shows that rainfall has actually declined over the past 50 years.

Norway is best equipped to deal with climate change

According to a country list drafted by The University of Notre Dame the country that is the least impacted by and/or best equipped to deal with climate change is Norway. Other winners are (in order of appearance): 2. New Zealand, 3. Finland, 4. Sweden, 5. Australia, and 6. Switzerland. Canada scores 13th place and the United States 15th.

Figure. Countries least and most at risk from climate change (picture from theecoexpert.co.uk)

The country list is highly correlated with a list of gdp. No surprise. On the one hand the index looks at the extent to which a country is exposed to climate hazards and how sensitive its systems and sectors are (such as water, food, human habitat, energy).

On the other hand the index takes into account how much a country can invest to deal with and adapt to its climate hazards. For example droughts, superstorms, migration, fire and civil conflicts. A country that can invest relatively easily in adaptation has a strong economy, a non-corrupt government, strong education systems and a good (it-)infrastructure.

The Balkans will be like the Middle East

Because of the ‘urban heat island effect’ cities are already warmer than their rural surroundings. If we do not curb emissions (Business-As-Usual scenario – RCP 8.5) by 2100 they will be much hotter still. Climate Central in 2017 created the interactive map below in partnership with the World Meteorological Organization.

Under the BAU-scenario cities in the Balkans will experience the most extreme temperature rise, varying between 7.5°C and 8.5°C increase. For example Budapest will reach an average summer daily maximum temperature of 32.2 °C (from 24.8°C ), Sofia 32.6°C (from 24.3°C) and Bucharest 36.4°C (from 28.1°C ). Temperature-wise this would transform the Balkans into the Middle East.

At their turn some cities in the Middle East will get so hot that they have no current-day equivalents. For example, Riyadh will reach 48 °C Celsius and Baghdad a blistering 49,5 °C .

The temperatures in the graph refer to average daily maximum temperatures over June, July and August on the Northern Hemisphere (Dec, Jan & Feb on the Southern Hemisphere).

Non-survivable humid heatwaves for over 500 million people

Researchers at MIT warn that if climate change remains unchecked (Business As Usual-scenario = RCP 8.5) over half a billion people will, from 2070 onwards, experience humid heat waves that will kill even healthy people in the shade within 6 hours. The Wet Bulb Temperature (WBT) would exceed 35°C (95°F), at which the body – of any mammal – cannot cool itself, overheats and shuts down.

Three regions were studied: China (2018), South Asia (2017) and the Persian Gulf (2015). The researchers predict (at RCP 8.5) WBT exceeding 35°C about once every decade for the Northern Plains in China (400+ million people), at locations in the Chota Nagpur plateau, northeastern India, and Bangladesh in South Asia (70+ million people). Persian Gulf regions that would be affected include cities such as Doha, Qatar, Abu Dhabi, Dubai (UAE) and Bandar Abbas (Iran).

Figure. 3 regions studied, worst areas in dark red.

The total number of people affected will be higher than 0.5 billion. A study in Nature (2017) identifies regions worldwide that are likely to exceed the survivability threshold from 2070 onwards (see Fig. 2). These also include the Eastern United States, Northern Latin America and Northern Australia.

Figure 2.Annual probability of occurrence of extreme humid heat waves at 4°C  warming relative to 1861–1880 (which is likely by 2070 under RCP 8.5 scenario) of the level AT55°C (Apparent Temperature), which roughly corresponds to a Wet Bulb Temperature of 33°C, with peaks exceeding WBT of 35°C. Orange means that such temperatures will be reached every other year on average. Source.

Wet bulb temperatures higher than 33.5°C for more than a few hours have not been measured in human history (yet). In 2015 there was a severe episode in South Asia with 30°C WBT. This led to 3,500 deaths. According to this article the largest hospital in Karachi was receiving 1 patient per minute and the morgue was overflowing.

Would airconditioning be to avail? Podcast Ashesashes describes that a ‘perfect storm’ will hit power supply at extreme temperatures. Airconditioning at high temperatures leads to more than 20% extra power demand, while at the same the power grid becomes less effective, nuclear and gas fuel plants provide less power because of warmer cooling water and transformers are more likely to overheat leading to power outages. Also, it is hard to see how renewable energy could meet the peak demand. Without solutions, the areas mentioned would effectively become uninhabitable.

At the Business as Usual-scenario many billions of people would experience WBT higher than 32°C on a regular (e.g. yearly) basis, which is already deadly for the less fit and makes working outside impossible.

In 50-60 years New York will be like Arkansas, Minnesota like Kansas, and Stockholm like Paris

A study in Nature Communications (2019) finds that if greenhouse emissions continue unabated (RCP 8.5) climates in North America will shift on average 850 kilometers between now and 2080. That is, 14 kilometers per year. The northeast will tend to feel more like humid subtropical parts of the Midwest or southeastern U.S – warmer and wetter. Washington will be like northern Mississippi. San Francisco will be like L.A. And New York will be like northern Arkansas.

Figure. In 2080 you will have to travel 850 kilometers on average to find your current climate. Credit: Matthew Fitzpatrick/University of Maryland Center for Environmental Science

Another study from 2019 describes that in 2070 Minnesota’s signature forests might be lost altogether to prairies. Researchers describe that if we are to hit 667ppm CO2-equivalent greenhouse gases in 2070 Minnesota by then might resemble Kansas. They describe that the state’s tree cover would creep northward and the prairies that predominate in the southwest of the state would take over what was previously a mix of fields, deciduous woods and pine forests. Also, the say that climate is likely to change too fast for plant species to migrate to their new locations. Plant species would need help by moving them (sic!).

Figure. From forest to prairie in 50 years. Credit: Star Tribune, with sources from the University of Minnesota for forest Ecology.

When we turn to Europe, it is harder to find climate analogue studies. A Swedish government study from 2007 predicts (conservatively we might add in 2018) an average temperature rise by 2080 in between 3 and 5°C. Climate modelling based on these numbers would mean that the area around Stockholm would have a climate comparable to Northern France.

Consequences of a weakening gulf stream

The warm gulf stream is a current that brings warm water from the tropics to the poles, where it cools, sinks and returns southwards. It weakens because 1) warming makes water less dense and more buoyant and 2) fresh and cold water from the melting Greenland ice sheet disrupts the flow.

The warm gulf stream has weakened about 15% since 1950. Past collapses of the gulf stream have caused western Europe to descend into freezing winters. A significantly weakened system is associated with more – maybe much more – severe storms in Europe, faster sea level rise on the east coast of the US, increasing drought in the Sahel and collapsing deap sea ecosystems.

Figure. AMOC = gulf stream. Nature 556, pp180-181 (2018).

The system is said to be highly non-linear and has been associated with abrupt changes in temperature when disturbed, such as winter temperatures changing up to 10C within three years in some places.

Counterintuitively, the cooler water close to western Europe that is entailed in a weaker gulf stream helps warm air to flood into Europe from the south, thereby also possibly increasing summer heatwaves.

Mid-Pliocene conditions start in 2030

Under the Business-as-usual scenario (RCP 8.5) the future climates in 2030  will most closely resemble Mid-Pliocene climates, with surface temperatures 1.8 °C to 3.6 °C warmer than preindustrial temperatures. This means a climate that resembles the climate 3-3.3 million years ago, when CO2 -levels were at 400ppm – levels which we have crossed in 2016. Mid-Pliocene conditions will first emerge in continental interiors and in the decades afterward they will spread towards the coasts.

Figure: Temperature trends for the past 65 Ma and potential geohistorical analogs for future climates. By Burke et al. in Proceedings of the National Academy of Sciences (November 2018).

In 2100 the situation will be totally different. Under the RCP8.5 scenario, the climate from the past that best matches continental interiors by 2100 is the early Eocene climate. For these climate conditions, we have to go back abut 50 million years, when global mean annual surface temperatures were a whopping 13 °C ± 2.6 °C higher than preindustrial temperatures and there were swampy forests in the arctic.

Under the RCP4.5 emission scenario the climate stabilizes at mid Pliocene-like conditions.

Figure. 2050 analogies with earlier climates (RCP8.5)