Presentation on theme: "Global Warming: Old Science, New Science, Controversies and Solutions Steven Sherwood Climate Change Research Centre University of New South Wales."— Presentation transcript:
Global Warming: Old Science, New Science, Controversies and Solutions Steven Sherwood Climate Change Research Centre University of New South Wales
1. The basic science 2. Lessons from history 3. What the future holds 4. Possible actions 5. Questions Steven Sherwood Climate Change Research Centre University of New South Wales
3 Is the science settled? Climate science involves many propositions. Some propositions are settled. Some are not.
4 How many experts* agree that humans are warming the planet? A) less than 30% B) 30-50% C) 50-70% D) 70-90% E) more than 90% *scientists actively publishing in climate-related fields, employed at universities or research laboratories.
5 How many experts* agree that humans are warming the planet? E 2009 Survey by the University of Illinois: 97% (Petitions supposedly showing thousands of scientists in opposition are bogus)
6 Scientific Bodies Concur So what? American Association for the Advancement of ScienceAmerican Chemical SocietyAmerican Geophysical UnionAmerican Institute of Biological SciencesAmerican Meteorological SocietyAmerican Society of AgronomyAmerican Society of Plant BiologistsAmerican Statistical AssociationAssociation of Ecosystem Research CentersBotanical Society of AmericaCrop Science Society of AmericaEcological Society of AmericaNatural Science Collections AllianceOrganization of Biological Field StationsSociety for Industrial and Applied MathematicsSociety of Systematic BiologistsSoil Science Society of AmericaUniversity Corporation forAtmospheric ResearchIntergovernmental Panel on Climate Change U.S. Global Change ResearchProgram. And this is just in the US. Every US Academy or European equivalent report on the subject since 1979 has also concluded that human activities will or have warmed the climate. Peer reviewed literature shows near unanimity.
7 Facts lost in media coverage Warming continues unabated Recent “scandals,” which have received so much coverage, have nothing to do with the theory or evidence for global warming. Global Warming was predicted as early as the 1800’s but has occurred faster than predicted. Published, consensus warming predictions from 1990 onward have been accurate so far. 7
8 Knew about “dark heat” (infrared radiation) Surface heat balance Figured out the greenhouse effect and used “Greenhouse” analogy 1824 Joseph Fourier [1768- 1830] 8
9 First calculation of warming by CO 2 increase First clear recognition of water vapour as a warming amplifier Made significant errors, but grasped the fundamentals 1896 Svante Arrenhius [1859- 1927]
10 Found upward trends in temperature and CO 2 measurements Proposed that the warming predicted by Arrhenius was already underway Colleagues were sceptical. 1938 Guy Stewart Callendar [1898-1964]
11 Discovery that oceans were not taking up all the CO 2 Confirmation of radiative effects of CO 2 First accurate calculation of global warming New geologic evidence that climate changes easily. 1950-1970 Last big theoretical issues resolved
Measurements of three greenhouse gases from air bubbles trapped in polar ice IPCC 2007 1. We are altering the composition of our atmosphere, at least 10x faster than the fastest natural change. agricultur e range during ice ages
Cumulative emissions since 1850 (fossil fuel burning and cement manufacture) CO 2 emissions began in late 19th century
Timing and amounts match. ✓ There is also chemical evidence proving the CO 2 came from fossil fuels. CO 2 rise also began in late 19th century IPCC 2001
2. These extra gases are retaining more heat within the Earth system. Greenhouse effect of CO 2 Greenhouse effect of ozone Satellites can directly measure this. It has increased by nearly 1 million GigaWatts due to greenhouse gas increases. Where is this heat going? C.A. Beichman, ed., JPL Publication 96-22, 1996 Greenhouse effect of methane
High School Physics When you put heat Q in to something with heat capacity C, the temperature T rises by Q ÷ C. Greenhouse gases are adding 2x10 22 J of energy each decade. Directly measured ✓ Nearly all is going into the top 100 meters of the world’s oceans. Observed ✓ C ≈ 10 23 J/ o C This yields a warming rate of 0.2C per decade. Not rocket science.
(IPCC = Intergovernmental Panel on Climate Change) The IPCC published a prediction in 1990 (a rise of about 0.2C per decade) Prediction by IPCC 1990 global observations Did it come true?
(More evidence that this warming was due to greenhouse gases) Observed change If caused by greenhouse gases If caused by sun, clouds, volcanoes stratosphere cooled stratosphere cools ✓ no change in stratosphere X continents warmed more than ocean continents warm more than ocean ✓ high latitudes warmed more high latitudes warm more ✓ tropics warm more X night warms more night warms more ✓ day warms more X And...observations show solar brightness same now as in1979.
3. 20th century warming is unequivocal... 19782004 Qori Kalis glacier 1960 2005 Matter- horn Nearly all glaciers have retreated since 1800’s. 14m avg thinning since 1950.
Oerlemans 2005 Kaufmann et al 2009 3. 20th century warming is unequivocal... and unusual...and mirrors CO 2. Huang et al 2000 From glacier lengths From borehole temperature
Impacts happening already (and will intensify with more warming) Rain heavier and less reliable*, droughts more common* Shifting climate zones* → maladapted vegetation, wildfires* Sea level rise* Ocean turning more acidic, slowing coral growth* More humid summers*, milder winters*, longer growing seasons, more record heat*, less record cold* Decreasing snowpack*, water supplies Species migrating away from Tropics* Stronger hurricanes Smaller birds!* (and many other examples) *reported in Australia
Impacts happening already (and will intensify with more warming) Many links unproven/exaggerated, and We are coping. BUT: Many impacts are straightforward, and They could become much worse with more warming.
If these facts are so clear, why do so many in the media say global warming is bunk?
The Copernican Revolution Nicolas Copernicus (1473-1543) new observations suggest that Earth orbits the Sun. Published on his deathbed. X
The Copernican Revolution Johannes Kepler discovers simple patterns, elliptical orbits (1609) 1610: Galileo’s telescope reveals moons of Jupiter, sunspots, remoteness and fullness of the heavens.
The Copernican Revolution Sir Isaac Newton (1686): gravity explains Kepler’s observations perfectly.
“But the decision was not exclusively, or even primarily, a matter for astronomers, and as the debate spread from astronomical circles it became tumultuous in the extreme. To most of those who were not concerned with the detailed study of celestial motions, Copernicus’ innovation seemed absurd and impious. Even when understood, the vaunted harmonies seemed no evidence at all. The resulting clamour was widespread, vocal, and bitter.” - T. S. Kuhn, 1957
29 Acceptance by scientists only after generational change “Successive generations of astronomers, decreasingly predisposed by experience and training to take the Earth’s stability for granted, found the new harmonies a more and more forceful argument for its motion.” --T. S. Kuhn “Authorities” most often heard denying human role in climate:
30 Bogus but convincing counter-arguments “the slightest jar of the Earth would see cities and fortresses, towns and mountains thrown down.” “Neither an arrow shot straight up nor a stone dropped...would fall perpendicularly” --J. Bodin, 1597 CO 2 lags temperature in ice cores, proving it has no effect Climate and CO 2 show no correlation over the last 10 years Recent snowstorms in the US and UK etc. 30 XX
31 Refusal to acknowledge evidence Scientists and others often refused to look through Galileo’s telescope. “But as for myself, I shall not believe that there are such proofs until they are shown to me.” -- Cardinal Bellarmine, 1615, long after Galileo’s discoveries. Repeated false claims the world is “cooling” or that there is “no evidence” linking CO 2 and climate. Very few critics have looked at an IPCC report or spoken to mainstream scientists.
32 Clinging to elaborate, unlikely alternatives Solar control of climate through cosmic rays, creating ions which somehow grow into cloud particles which somehow affect the total amount of cloud, causing all warming. And somehow the known effect of CO 2 does not occur. Epicycles, equants, deferents 32
33 Scientists’ views stable, public’s vary. Educated people believed in round Earth thoughout last two millenia Scientists gradually accepted a moving Earth, with no going back. Popular resurgence of flat-Earth belief in 19th- 20th centuries Scientist views consistent (with increasing confidence) since 1950’s Recent retrogression of public views Media scare stories of cooling in 1960’s
34 Ad hominem attacks and conspiracy theories Copernicans widely accused of atheism (late 1500’s onward) Allegations of conspiracies to deceive the public with complicity of the media (1800’s onward) Climate scientists accused of being socialists/communists Scientists accused of conspiracy to seek power, world government 34
35 Politics: closing of ranks 1615: Cardinal Bellarmine says “we should rather admit that we did not understand [scripture] than declare an opinion to be false which was proved to be true.” 1616: Bellarmine declares Copernicanism false. 2007: Malcolm Turnbull and John McCain take global warming seriously 2008: McCain and Palin: “Burn baby burn” 2010: Turnbull out. Increasing denial among conservative politicians. 35
36 Resistance from powerful interests Catholic church forbids teaching or belief of heliocentrism, 1616-1822. Forced recantation by Galileo, 1633. Government investigations of scientists (2006, 2010) “Gag orders” for scientists at NASA and NOAA in the US Government revision of scientific reports to water them down Fossil-fuel industry disinformation campaigns 36 These actions came only after the scientific evidence had become overwhelming. Other inconvenient truths: Dangers from lead additives Risks of overfishing Ozone loss from CFCs and nitric oxide HIV causing AIDS Long-term brain damage to boxers Smoking and lung cancer
37 Timelines expert concensus idea proposed counterattacks on science public concensus 1500180016001700 1900220020002100
Baby temperature Time blanket thrown on ? ? How long/far does the warming go? We need a theory of heat transport! Greenhouse gases work like blankets What about the future?
Theory of planetary heat transport, aka “climate model” Without one, you cannot make scientific predictions. So-called “sceptics” do not bother with them. All the ones we have predict substantial future greenhouse warming. Data on past climate changes confirm the large responses to these gases. Many regional changes cannot be predicted yet.
Carbon dioxide What if business as usual continues? Tripling of CO 2 is likely Warming of 4C or more is likely by 2100, but could be lower or higher. last ice age −5 C do nothing + unlucky do a lot + lucky Greenland probably melts Sydney summers like Townsville now Tropics inhabitable??
Surprises? Uncertainties? Climate sensitivity anomalously low or high? Unexpected collapse of ice sheet? Sudden release of frozen methane deposits + massive warming? Rapid shift to new ocean circulation pattern? Collapse of Amazon or other ecosystem? All deemed rather unlikely. None are impossible. There could be others. Any could make climate change dramatically worse.
42 Is there any hurry? CO 2 -induced climate change is effectively irreversible Emissions are growing faster each year To avoid “dangerous” warming of 2C, emissions would have to begin declining within about a decade. Artificial cooling of the climate is a possibility (but won’t solve acidification) 42
43 Much analysis has been done Source: McKinsey Climate Change Special Initiative, 2007.
44 Is the economics settled? Economists/analysts agree: Multiple responses would be needed. Conservation is the most economical and rapid one. A serious policy must have a price on carbon. Many helpful technologies already exist, but more will be needed down the track. Abatement of future warming can be achieved if we are willing to accept 5- 10% slower economic growth.