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Ursprungligen postat av
skogshuggar3n
I förhållande till den valda referensperioden ja. Det står väl till och med i artikeln att det finns motsvarande värmeperioder under 30-talet t.ex.
Skriver man inte också något i stil med att syftet inte är att påvisa AGW utan, med förutsättningen att det är människan som ligger bakom uppvärmningen, illustrera vad som händer i ett varmare klimat.
Oavsett allt så får man som vanligt ta fram det stora saltkaret.
Alltså... "Syftet inte är att påvisa AGW"... Jag undrar om du läst artikeln ordentligt. Först vill jag bemöta din text om 30 - talet. Visst, några år kring 30 - talet var varmare än medel för referensperioden (som de också motiverar). Det ledde mycket riktigt till en högre andel väder i utkanterna av Bell - kurvan.
Såhär skriver de bl.a
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Temperature anomalies are “noisy” for the United States because of the small area of the contiguous 48 states (less than 1.6% of the globe), yet we can discern that the long-term trend toward hot summers is not as pronounced in the United States as it is for hemispheric land as a whole. Indeed, the extreme summer heat of the 1930s, especially 1934 and 1936, is comparable to the United States temperature in the most extreme recent years....
... The large 1930s and 1940s anomalies in the United States do not obviate the conclusion that recent global warming, with high probability, is responsible for recent extreme anomalies. Our*SI Text*shows maps of temperature anomalies for 6*y with the greatest “hot” area (1931, 1934, 1936, 1941, 1947, 1953) in that early warm period. Those years were warmer (globally and in the United States) than the 1951–1980 mean, so it is not surprising that the area with 3σ anomalies was greater than in the 1951–1980 climatology. The year with the largest area of 3σ anomalies was 1941, when it reached 2.7% of Northern Hemisphere land area. This compares with recent values as great as 20% and a recent average of about 10%.
Min fetning.
Resultaten från denna studie är inte beroende av orsaken till uppvärmningen, vilket också påtalas i artikeln. Det som görs tydligt är att extremvädren blir vanligare med en varmare värld, vilket antropogen uppvärmning leder till.
Här kommer några fler intressanta delar från artikeln:
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A remarkable feature of*Fig.*3*is the large brown area (anomalies >*3σ), which covered between 4% and 13% of the world in the six years 2006–2011. In the absence of climate change, and if temperature anomalies were normally distributed, we would expect the brown area to cover only 0.1–0.2% of the planet. In*Fig.*3,*Top, the temperature anomalies in a mid-year of each of the three decades in the 1951–1980 base period, confirms that such extreme anomalies were practically absent in that period. Occurrence of extreme anomalies (>*+3σ) in recent years is an order of magnitude greater than during the 1951–1980 base period.
The recent spate of 3σ events raises several questions. What does the temperature anomaly distribution look like, how is it changing, and how important is a +3σ anomaly? Well-publicized extreme conditions in Texas in 2011 and around Moscow and in the Middle East in 2010 had summer temperature anomalies reaching the +3σ level (Fig.*3), suggesting that an increase of such extreme events may have large practical impacts.
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The probability distribution shifts to the right in each successive decade in the past 30*y and the distribution becomes broader, with the broadening adding to the increase of hot anomalies. Occurrence of 3σ, 4σ, and 5σ anomalies, practically absent in 1951–1980, is substantial in the past decade, consistent with the large brown areas in*Fig.*3. Occurrence of seasons cooler than the 1951–1980 average (temperature anomaly <*0*°C) is greatly diminished in recent decades, as we will quantify below.
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Probably the most important change is the emergence of a new category of “extremely hot” summers, more than 3σ warmer than the base period mean.*Fig.*6*illustrates that +3σ anomalies practically did not exist in 1951–1980, but in the past several years these extreme anomalies have covered of the order of 10% of the land area.
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The increase, by more than a factor 10, of area covered by extreme hot summer anomalies (>*+3σ) reflects the shift of the anomaly distribution in the past 30*y of global warming, as shown succinctly in*Fig.*4. One implication of this shift is that the extreme summer climate anomalies in Texas in 2011, in Moscow in 2010, and in France in 2003 almost certainly would not have occurred in the absence of global warming with its resulting shift of the anomaly distribution. In other words, we can say with high confidence that such extreme anomalies would not have occurred in the absence of global warming.
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The hot tail of the temperature anomaly distribution shifted by more than +1σ in response to the global warming of about 0.5 °C over the past three decades. Additional global warming in the next 50*y, if business-as-usual fossil fuel emissions continue, is expected to be at least 1 °C (4). In that case, the further shifting of the anomaly distribution will make +3σ anomalies the norm and +5σ anomalies will be common.
Min fetning igen. Det är liksom inget kontroversiellt inom vetenskapen att ökade koncentrationer av växthusgaser leder till uppvärmning. Det råder konsensus. Vilket är uppenbart genom den textsnutt som är fetad här nederst.
