Researchers from the University of Hawaii have estimated the year when we depart the climate variability we have historically known for cities around the globe. But the study also identifies that the planet's oceans have already passed their climate departure point, and that the greatest impact of global warming will be felt in biodiversity and ecosystems in the tropics.
In a study published in Nature - The projected timing of climate departure from recent variability (abstract) - researchers lead by Camilo Mora from the Geography Department at the University of Hawaii sought to identify the point at which the climate at 54,000 locations on Earth will exceed the bounds of historical variability. They used a baseline period of 1860 to 2005 to determine natural temperature variability. Using results averaged from 39 different climate models, they then determined for each location measured the year point in which the coldest years are likely to be consistently hotter than any of the past 150 years.
Cities to feel the heat of unexperienced climate this century
The study clearly shows that this century, no matter where we live, we will all experience a new climate beyond anything human civilization has experienced over thousands of years. For business as usual emissions scenario (RCP85) the mean year is 2047 for the planet. If we take action to drastically reduce and stabilise emissions with Scenario RCP45, the mean year is pushed back to 2069. The 39 models were surprisingly in agreement with no more than 5 year standard error at any location. The global average at year 2047 has a +/-14 years (standard deviation).
Study co-author Abby Frazier told the ABC, "We took a very conservative approach to this whole study by using, the absolute min and max values and using all the possible models that are out there," she said. "We didn't even think that this date [would] happen in the next century so we were really surprised that the 2047 [deadline] was so early. I mean this is within our lifetimes. [We were] even more surprised that even if we take action now, the 2069 is still happening within this century."
But cities in the tropics are likely to pass the departure point much earlier than cities in the mid latitudes. Manokwari in the West Papuan province of Indonesia will pass the RCP85 point in 2020 but with mitigation this date will be pushed back to 2025. Kingston Jamaica will follow in 2023 or 2028 with mitigation. Island nations such as Palau, Micronesia, Solomon Islands, Haiti, Maldives, Marshall Islands, Seychelles, Samoa, Bahamas, Tuvalu all follow in the 2020s along with cities in equatorial countries like Guinea, Gabon, Liberia, Ghana, Bolivia, Central African Republic, Singapore, Malaysia Nigeria, Sri Lanka.
"The results shocked us. Regardless of the scenario, changes will be coming soon," said lead author Camilo Mora. "Within my generation, whatever climate we were used to will be a thing of the past."
By 2050 it is projected that over 5 billion people, mostly in developing countries, may be experiencing extreme climate if business as usual emissions continue. With mitigation undertaken this reduces to about 1 billion people.
"Our results suggest that countries first impacted by unprecedented climates are the ones with the least capacity to respond," said coauthor Ryan Longman. "Ironically, these are the countries that are least responsible for climate change in the first place."
Extreme climate will produce changes and availability in the supply of food and water, human health, wider spread of infectious diseases, heat stress, conflicts, and substantial challenges to economies. Just as species attempt to relocate to a more suitable climate, we will see movements of people which is already throwing up questions such as What should be done about climate change refugees? (Toronto Star)
Figure 1a: An example profile of projected timing of climate departure for a location in the North Atlantic. Historical climate bounds are exceeded for 3 years from 2012, then for 11 years from 2023. By 2036 climate departure occurrs with all temperatures outside of historical boundaries. (C. Mora et al (2013))
For Australia the climate departure years were calculated as:
|City||RCP85 (Business as Usual)||RCP45 (mitigation)|
Camilo Mora and colleagues highlight the human inequalities:
"The fact that the earliest climate departures occur in low-income countries (Fig. 5b) further highlights an obvious disparity between those who benefit economically from the processes leading to climate change and those who will have to pay for most of the environmental and social costs. This suggests that any progress to decrease the rate of ongoing climate change will require a bigger commitment from developed countries to decrease their emissions but will also require more extensive funding of social and conservation programmes in developing countries to minimize the impacts of climate change. Our results on the projected timing of climate departure from recent variability shed light on the urgency of mitigating greenhouse gas emissions if widespread changes in global biodiversity and human societies are to be prevented."
Figure 5: Susceptibility of societies to climate departures, and economic
capacity to respond. (C Mora et al (2013)
Oceans already in a new climate
The study looked at more than just the land surface temperatures for it's results. Variables analysed included near-surface air temperature, precipitation, evaporation, transpiration, surface upward sensible heat flux, and two ocean related measurements: surface sea water potential temperature and pH.
These latter two measurements revealed that when taken together, the world's oceans have already passed THEIR mean climate departure date in 2008. From the paper:
"The projected timing of the ocean's climate departure was pushed forward to this decade when pH was considered alongside sea surface temperature. Global mean ocean pH moved outside its historical variability by 2008 (63 years s.d.), regardless of the emissions scenario analysed (Extended Data Fig. 4). This result, which is consistent with recent studies, is explained by the fact that ocean pH has a narrow range of historical variability and that a considerable fraction of anthropogenic CO2 emissions has been absorbed by the ocean."
In a related study published by Camilo Mora and colleagues published in the journal PLOS Biology - Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century (Full Study), the authors summarise their results:
"Climate change caused by human activity could damage biological and social systems. Here we gathered climate, biological, and socioeconomic data to describe some of the events by which ocean biogeochemical changes triggered by ongoing greenhouse gas emissions could cascade through marine habitats and organisms, eventually influencing humans. Our results suggest that the entire world's ocean surface will be simultaneously impacted by varying intensities of ocean warming, acidification, oxygen depletion, or shortfalls in productivity. Only a very small fraction of the oceans, mostly in polar regions, will face the opposing effects of increases in oxygen or productivity, and almost nowhere will there be cooling or pH increase. The biological responses to such biogeochemical changes could be considerable since marine habitats and hotspots for several marine taxa will be simultaneously exposed to biogeochemical changes known to be deleterious. The social ramifications are also likely to be massive and challenging as some 470 to 870 million people – who can least afford dramatic changes to their livelihoods – live in areas where ocean goods and services could be compromised by substantial changes in ocean biogeochemistry. These results underline the need for urgent mitigation of greenhouse gas emissions if degradation of marine ecosystems and associated human hardship are to be prevented."
Watch Professor Jason Hall-Spencer, University of Plymouth talking on Ocean Acidification in this video done for IPSO:
The fact is we are driving a huge marine extinction here with nutrient pollution, ocean acidification and over-exploitation of marine resources. The latest research from the International Programme on the State of the Ocean (IPSO)/IUCN review of science on anthropogenic stressors on the ocean, released on October 3, conclude the condition of the ocean is even worse than the conclusion reached by the UN climate change panel the IPCC. IPSO warns that the ocean is absorbing much of the heat of global warming and unprecedented levels of carbon dioxide and warn that the cumulative impact of this with other ocean stressors is far graver than previous estimates.
It is not just a matter of increasing sea surface temperatures and changing pH. Climate change and nitrogen runoff is also causing decreasing oxygen levels in the ocean. Combining this with other chemical pollution and rampant overfishing undermines the ability of the ocean to withstand 'carbon perturbations', severely compromising the ocean in its role as a Earth climate system 'buffer' say the marine scientists.
Watch Professor Robert Diaz, Virginia Institute of Marine Science on Ocean Dead Zones for IPSO:
Professor Alex Rogers of Somerville College, Oxford, and Scientific Director of IPSO
said in a media release (PDF): "The health of the ocean is spiraling downwards far more rapidly than we had thought. We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated. The situation should be of the gravest concern to everyone since everyone will be affected by changes in the ability of the ocean to support life on Earth."
Tropical biodiversity under siege by warming climate
While Arctic and Antarctic polar regions are warming up at 2 or 3 times the global average, these areas already experience wide temperature variation. The Tropics however experience only small variations in temperature. Global warming heating the tropics will push these areas much sooner past the climate departure point into unknown territory.
The tropics also host a large variety of biodiversity hotspots and these will be hit particularly hard by a warmer climate according to Mora and his colleagues.
The study found that projected timing of climate departure in marine and terrestrial biodiversity hotspots will occur one decade earlier than the global average under either emissions scenario.
According to the authors, corals, mangroves and Seagrasses lead the way in being threatened, "Coral hotspots will experience the earliest arrival of unprecedented climates: 2050 under RCP45 (about 23 years earlier than the global average), or 2034 under RCP85 (about 17 years earlier than the global average)"
Scientists already say that Global Warming imperils coral reefs: 2 degrees warming is too hot.
The study says:
"The earliest emergence of unprecedented climates in the tropics and the limited tolerance of tropical species to climate change are troublesome results, because most of the world's biodiversity is concentrated in the tropics...these results suggest that the overarching effect of climate change on biodiversity may occur not only as a result of the largest absolute changes in climate at high latitudes but also perhaps more seriously from small but prompt changes in the tropics. In short, the tropics will be highly vulnerable to climate change for at least three reasons: first, the earliest emergence of unprecedented climates will be there; second, tropical species are more vulnerable to small climate changes; and third, this region holds most of the Earth's species."
Figure 3: The projected timing of climate departure from recent variability
in global biodiversity hotspots. Green bars are for terrestrial species using mean annual air temperature; Blue bars are for marine species using sea surface temperatures. Plots are centred at the global mean year for atmospheric (green numbers) and marine (blue numbers) environments.
Even tropical insects may suffer the impacts of a warming climate with a study in 2012 finding that Tropical insects may face catastrophic reduction in reproduction with climate change. Skeptical Science reported on Global warming impact on tropical species greater than expected in October 2010.
Already scientists have identified that fish species are migrating out of the tropics heading for cooler waters, and that Species biodiversity is under threat from the velocity of climate change. Sea level rise will add a hidden impact on Biodiversity and Habitat loss particularly in the Asian and Pacific regions.
Climate change is proceeding at such a pace that Earth's biological systems have little capacity to adapt through evolution. The changes are forcing species to either move in an attempt to track suitable climates, stay and try to adapt to the new climate, or go extinct. For a great proportion of species extinction looms.
"This work demonstrates that we are pushing the ecosystems of the world out of the environment in which they evolved into wholly new conditions that they may not be able to cope with. Extinctions are likely to result," said Ken Caldeira of the Carnegie Institution for Science's Department of Global Ecology. Caldeira was not involved in this study. "Some ecosystems may be able to adapt, but for others, such as coral reefs, complete loss of not only individual species but their entire integrity is likely."
This study shows that we need to adapt and prepare for the changing climate, but we also need to urgently start reducing carbon emissions and our carbon footprint to give more time for adaptation. We are looking at substantial loss of biodiversity with the onset of a 6th global mass extinction. Mitigation action is essential to assist biodiversity conservation programs.
Climate Departure Years for Cities in order of RCP8.5 (Business As usual) ranking
|Sao Tome and Principe||Sao Tome||2025||2028|
|Dominican Republic||Santo Domingo||2026||2033|
|Brunei||Bandar Seri Begawan||2027||2035|
|Central African Republic||Bangui||2028||2036|
|Republic of the Congo||Brazzaville||2028||2038|
|Trinidad and Tobago||Port of Spain||2032||2044|
|Antigua and Barbuda||St. John's||2033||2047|
|El Salvador||San Salvador||2033||2049|
|Papua New Guinea||Port Moresby||2033||2043|
|Saint Kitts and Nevis||Basseterre||2033||2047|
|Saint Vincent and the Grenadines||Kingstown||2033||2046|
|United Arab Emirates||Abu Dhabi||2033||2047|
|Tanzania||Dar es Salaam||2034||2053|
|Costa Rica||San Jose||2037||2058|
|South Africa||Cape Town||2038||2060|
|Vietnam||Ho Chi Minh City||2039||2062|
|Andorra||Andorra la Vella||2044||2070|
|San Marino||San Marino||2047||2072|
|USA||New York City||2047||2072|
|Brazil||Rio de Janeiro||2050||2079|
|Bosnia and Herzegovina||Sarajevo||2051||2079|
- University of Hawaii media release, 9 October 2013 - Study in nature reveals urgent new time frame for climate change
- Camilo Mora, Abby G. Frazier, Ryan J. Longman, Rachel S. Dacks, Maya M. Walton, Eric J. Tong, Joseph J. Sanchez, Lauren R. Kaiser, Yuko O. Stender, James M. Anderson, Christine M. Ambrosino, Iria Fernandez-Silva, Louise M. Giuseffi, Thomas W. Giambelluca. The projected timing of climate departure from recent variability. (abstract, Nature, 2013; 502 (7470): 183 DOI: 10.1038/nature12540
- Stephanie Small, ABC, 10 October 2013 - Researchers warn record temperatures could hit as early as 2020
- IPSO media release, 3 October 2013 - Latest Review of Science reveals Ocean in critical state from cumulative impacts (PDF)
- Camilo Mora et al (2013), PLOS Biology - Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century (Full Study)
- Image of Global Map of cities and City data list courtesy University of Hawaii - the Timing of New Climates
- All other images used from C Mora et al (2013). Review copy of Nature paper kindly provided by C Mora.