Las actuales políticas climáticas son altamente ineficaces dado el fuerte componente natural del cambio climático

“The future is unknowable, but the past should give us hope” Winston Churchill (1958)

Karl Popper’s falsifiability criterion for science requires that hypotheses not only explain known evidence, but also must be testable by evidence still unknown. However, a problem arises when any failed ex-ante prediction made by a hypothesis, can be post-hoc explained in multiple ways leaving the hypothesis nearly intact. An example is the pause in global warming that took place between 2001-2013, while accelerated warming was the CO2-hypothesis outstanding prediction for the 21st century (IPCC-FAR, 1990). The pause was explained in multiple ways (see: Nature Climate Changevol. 4, issue 3, 2014, and Nature’s “Focus: Recent slowdown in global warming“). To meet Karl Popper’s scientific criterion, the CO2hypothesis of climate change must make predictions that cannot be post-hoc explained when they fail. When demanding urgent action on CO2emissions, the predictions that can falsify the hypothesis are being made for a period ending in 2100, more than 80 years away. Its falsifiability is being removed until it no longer matters for present policy decisions.

This article deals with scientific forecasting of future climate change and its consequences. As with any other activity, forecasting has been the subject of systematic studies, and three of the foremost experts in forecasting principles have established the golden rule of forecasting: “be conservative by adhering to cumulative knowledge about the situation and about forecasting methods”(Armstrong et al., 2015). Research has shown that ignoring the guidelines deduced from the golden rule greatly increases forecasting error. However, climate forecasting is dominated by radical predictions, many of which are absurd, yet they are given disproportionate positive attention. Two of the authors (Green & Armstrong, 2007) analyzed the IPCC-Fourth Assessment Report, concluding that its forecasts were not the outcome of scientific procedures, but “the opinions of scientists transformed by mathematics and obscured by complex writing,” and warned that research on forecasting has shown that experts’ predictions are not useful in situations involving uncertainty and complexity. Previous research by Philip E. Tetlock had already demonstrated that expert forecasting is usually worse than basic extrapolation algorithms, and that there is a perverse inverse relationship between fame and accuracy in forecasting (Tetlock, 2005). J. Scott Armstrong went further and in 2007 challenged the IPCC prediction of 3°C/century (IPCC-TAR, 2001) with a no-change forecast for the next 10 years (2008-2017). Using the UAH dataset and judging by cumulative absolute error, the no-change forecast reduced forecast errors by 12% compared to the IPCC projection, showing that the IPCC projection had no value, since it was beaten by a no-change forecast (Climate tipping alarm vs scientific forecasting).

The first eight articles in this series analyzed the cumulative knowledge about climate change necessary for conservative forecasting.

1. The Glacial Cycleis necessary to understand our interglacial evolution and the role of Milankovitch forcing.
2. The Dansgaard-Oeschger Cycle researches the causes and consequences of the most abrupt climatic changes in the past.
3. Holocene Climate Variability (A and B) analyzes climate change during our interglacial.
4. The 2400-year Bray Cycle (A,B, and C) describes the major solar cycle that has determined important climatic shifts in the past, impacting human societies.
5. The 1500-year Cycleadds a much studied and little understood non-solar climate cycle, of a proposed tidal-oceanic origin, and its relationship to the Dansgaard-Oeschger cycle.
6. Centennial to Millennial Solar Cycles fills the gap of shorter solar cycles, of which the millennial cycle shows a big climatic effect on the Early and Late Holocene.
7. Climate Change Mechanisms analyzes the way the planet responds to different climate forcings and internal variability, including the 60-year oceanic oscillation that has characterized climate change for the past centuries.
8. Modern Global Warming describes the features of climate change since the Little Ice Age and the perceptible effect of anthropogenic forcing for the past seven decades.

With that knowledge we can attempt to conservatively forecast future climate change for the next decades.

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Claims of sinking nations, hordes of climate refugees, and a new normal every time there is an extreme weather event, are wildly exaggerated and agenda-driven. The highest return for our limited resources is very likely to come from adaptation policies, and no-regrets policies. Policies to prevent or reduce climate change are destined to be highly ineffectual given the strong natural component of climate change, as the past demonstrates.

Projections

1) Human CO2emissions are stabilizing. Peak coal and oil, and current trends make a decrease in emissions very likely before 2050. Atmospheric CO2levels should reach 500 ppm but might stabilize soon afterwards.

2) According to solar cycles, solar activity should increase after the present extended solar minimum, and 21st century solar activity should be as high or higher than 20th century. A mid-21st century solar grand minimum is highly improbable.

3) Global warming might stall or slightly reverse for the period 2000-2035. Cyclic factors suggest renewed warming for the 2035-2065 period at a similar rate to the last half of the 20th century. Afterwards global warming could end, with temperatures stabilized around +1.5°C above pre-industrial, and a very slow decline for the last part of 21st century and beyond.

4) The present summer Arctic sea ice melting pause might continue until ~ 2035. Renewed melting is probable afterwards, but it is unlikely that the Arctic summer will become consistently ice free even by 2100.

5) The rate of sea-level rise can be conservatively projected to a 290 mm increase by 2100 over 2000 levels. Most rates published are extremely non-conservative and very unlikely to take place.

6) Climate change should remain subdued and net positive for the biosphere for the 21st century. Adaptation is likely to be the best strategy, as it has always been.

References

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