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onsdag 17 augusti 2016

NASA:s senaste siffror om global medeltemperatur

Washington Post rapporterade igår om NASA:s senaste siffror för global medeltemperatur.

Rekordnoteringarna har duggat tätt de senaste två åren, och siffran för juli 2016 blev av samma slag:
    “July 2016 was absolutely the hottest month since the instrumental records began,” tweeted Gavin Schmidt, who directs NASA’s Goddard Institute for Space Studies, which is responsible for temperature measurements.
Lite längre ned i samma artikel läser vi följande:
    The El Niño event ended this spring, and the planet’s temperature difference from normal is no longer as remarkably high as it was earlier in the year. But it still remains at record highs.
Den skenbara motsägelse som kan skönjas mellan Schmidts uttalande och det senare citatet om att "the planet’s temperature difference from normal is no longer as remarkably high as it was earlier in the year" upplöses då vi inser att det senare till skillnad mot det förstnämnda handlar om data som rensats från säsongsvariation.

Jag finner det en smula tragikomiskt hur legendariske nyhetsankaret och numera notoriske klimatförnekaren Åke Ortmark, mitt under den rekordmånad som juli 2016 var, twittrade om att media (i detta fall Svenska Dagbladet) borde uppmärksamma vad han menade var en pågående temperaturnedgång. Möjligen kan detta förstås som ett försök från Ortmark att bli först med att besanna en väldigt rolig profetisk artikel i satirtidskriften PNIS (Proceedings of the National Institute of Science) ett år tidigare.

fredag 13 februari 2015

Global medeltemperatur 2014

Det har varit mycket snack om 2014: var det vår planets varmaste år sedan mätningarna startade? Mycket pekar i den riktningen, men det finns flera olika mätserier avsedda att approximera global medeltemperatur, och resultaten är inte helt entydiga. Men diskussionen om detta är mest bara symbolisk, ty det exakta svaret på frågan spelar mycket liten roll. Klimatforskaren Gavin Schmidt (vars klokskaper om förhållandet mellan vetenskap och politik jag citerade utförligt i min bloggpost Concerned world citizen häromveckan) förklarar på utmärkta bloggen RealClimate:
    The excitement (and backlash) over these annual numbers provides a window into some of problems in the public discourse on climate. A lot of energy and attention is focused on issues with little relevance to actual decision-making and with no particular implications for deeper understanding of the climate system. In my opinion, the long-term trends or the expected sequence of records are far more important than whether any single year is a record or not.
Med lite naiv optimism skulle man kanske ändå kunna hoppas att de höga värdena för 2014 skulle få klimatförnekarna i Stockholmsinitiativet och på annat håll att dämpa sig en smula i sitt (uppriktigt talat) imbecilla kacklande om temperaturplatå och uppvärmningspaus? Men nej, jag tror inte det.

Det kommer därför troligtvis att finnas ett fortsatt behov av att besvara sådant snack, och jag tänkte härmed bjuda på några länkar till illustrationer som pedagogiskt visar hur det förhåller sig: den globala uppvärmningen pågår för fullt.

När jag för några år sedan på Uppsalainitiativet (UI) satte ihop en liten FAQ med korta svar på typiska frågor och påståenden från klimatförnekarhåll, så lyfte jag särskilt fram ett par grafiska illustrationer som jag tycker håller ännu: Och här några mer dagsaktuella illustrationer:

onsdag 28 januari 2015

Concerned world citizen

    Concerned world citizen and professor of mathematical statistics (in that order)
So reads my motto on Twitter. There is a lot to be concerned about in the world. Two well-known global catastrophic risks are global warming and nuclear war. Another, less well-known but perhaps as serious, is the possibility of an uncontrolled AI breakthrough. But the main message I wish to convey with the motto is, despite the parentheses, contained in the last three words: in that order. Mathematics and science is very important, but a prosperous and happy future for humanity is, IMHO, even more important. Therefore I refuse, contra a not uncommon piece of advice, to keep quiet about my political views on science-related issues. The well-meaning concern - voiced by, e.g., climate scientist Tamsin Edwards in her blog post Climate scientists must not advocate particular policies1 - stems from the idea that if scientists express political ideas, then the credibility of their research risks being hurt, because it may raise suspicion about ideological contamination. I think that argument is not entirely without merit, and every scientist working in policy-relevant areas has her own choice to make on whether to take it to heart and act upon it, but to me personally it is overtrumped by an argument made by another climate scientist, James Hansen:
    Fourteen months later I gave another public talk - connecting the dots from global warming to policy implications to criticisms of the fossil fuel industry for promoting misinformation. This time my grandchildren provided rationalisation for a talk likely to draw ire from the administration. I explained that I did not want [them] to look back and say: "Opa understood what was happening, but he never made it clear."
In the opening paragraphs of their paper Science and policy: Crossing the boundary in the latest issue of Bulletin of the Atomic Scientists, Dale Jamieson, Naomi Oreskes and Michael Oppenheimer make a point similar to Hansen's:
    Consider the case of the late F. Sherwood Rowland, who, along with fellow chemist Mario J. Molina, first recognized the threat that chlorinated fluorocarbons (CFCs) posed to stratospheric ozone and potentially to life on Earth. (Rowland and Molina later won the 1995 Nobel Prize in Chemistry for their work, along with Paul J. Crutzen.) Some of Rowland’s colleagues criticized him for publicly stating that CFCs should be phased out. Although he did not advocate a specific policy instrument, these colleagues felt that by calling for a policy goal Rowland was illicitly stepping out of the world of science into the world of policy in which he did not belong.

    Imagine, however, that Rowland and Molina had published their research in a peer-reviewed journal and that, like most scientific work, it had then been largely ignored. Decades later, dermatologists and oncologists would have begun to notice an unexplained increase in rates of skin cancer. Epidemiologists would have analyzed the available data and concluded that there was in fact an epidemic of skin cancers around the globe, especially severe in Australia, southern Chile, and among white Africans. Meanwhile, plant pathologists would have noticed increased ultraviolet damage in agricultural crops; veterinarians would have noted increased rates of cataracts in farm animals. Scientists would then have searched for an explanation for this strange association of human, animal, and plant pathology. Eventually, someone would have come across Rowland’s work, connected the dots, and understood what was happening. Programs would then have been quickly put in place to measure stratospheric ozone, demonstrating that the ozone layer had been massively depleted. [...]

    This thought experiment, while counterfactual, is not fantastic. It is essentially what happened with asbestos and tobacco, and it could easily have been the case with chlorinated fluorocarbons as well.

Read the full paper by Jamieson et al here!

That same issue of the Bulletin is amazingly full-packed with wise and interesting discussions concerning the troublesome interface between science and politics. See for instance Gavin Schmidt's What should climate scientists advocate for from the same issue. I offer the following snapshots from that paper:
    Scientists and philosophers have long distinguished between descriptions of what "is" (derived from scientific investigations of the real world), what "ought" to be (based on one’s value system), and suggestions for what one "should" do in the face of this knowledge [...]. Despite this careful distinction between advocacy and facts, the term "advocate" is regularly used pejoratively in scientific circles and is frequently associated with the cherry-picking of science to support a preconceived idea. In order to avoid these connotations, scientists often go to great lengths to deny being advocates for specific policies.

    [...]

    In my view, it is impossible to divorce public communication from advocacy, and scientists should not even try. Instead, we should acknowledge and embrace the terminology and, in so doing, define clearly what our own values are and exactly what we are advocating for.

    [...]

    Responsible advocates are up-front about what is being advocated for and how the intersection of values and science led to that position. On the other hand, it is irresponsible to proclaim that there are no values involved, or to misrepresent what values are involved. Responsible advocacy must acknowledge that the same scientific conclusions may not lead everyone to the same policies (because values may differ). Assuming that one’s own personal values are universal, or that disagreement on policy can be solved by recourse to facts alone, is a common mistake.

Read Schmidt's full paper here!

Footnotes

1) I've commented on Edwards' blog post elsewhere.

2) He makes the same statement in his book Stoms of My Grandchildren, which I reviewed a few years ago.