Check: Effects of CO2 emissions on nature

According to popular greenhouse radiation theory, the increased emission of greenhouse gasses, in particular carbon dioxide (CO₂) causes global warming as well as other environmental effects such as reducing the pH ("acidification") of the oceans. Estimations of the warming effect of doubling the atmospheric CO2 concentration vary from ca. 0.5 to 5 °C. A popular so-called consensus estimation is ca. 3 °C equilibrium temperature increase. For the transient temperature increase (while it is happening), current estimations are around 1.5 °C.

We will split up the different aspects into separate articles and summarize the combined evidence on this page. If the conclusions of sub topics are modified, this page will be adapted as needed.

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1. Fact Check: CO2 emissions fingerprint on atmospheric CO2

Outcome: There is a reasonably good match; the current atmospheric CO₂ increase is almost certainly driven by man-made CO₂ emissions.

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2. Fact Check: CO2 emissions fingerprint on sea rise

Outcome: The average sea rise during the last 150 years does not match atmospheric CO₂ increase. It's unclear how much of recently increased sea rise is due to natural causes, and how much is due to CO₂ emissions.

Reality check of predictions: It's enlightening to compare published predictions with the reality. For example in 2014 the Dutch KNMI gave their outlook (their report p.57) based on IPCC predictions of local sea rise for two different emission scenarios, a high ("business as usual") and a low (strong CO2 reduction) scenario. Emissions in recent years until 2020 were around the high CO₂ scenario (see for example a figure in the journal Nature). Thus, hereunder we compare KNMI's local sea rise projection for that scenario.

Updated sea level observations. Average of 6 tide gauge stations along the Dutch coast for the period 1901 – 2018, compared with expected sea rise after 2000 based on CO2 models.

It's now obvious that the foreseen increase of sea rise was hugely overestimated. The recent trend line of measurements is still not or hardly bent upwards.

However, an insignificant increase in the rate of sea rise may be just a not-yet significant increase; and sea rise lags behind on temperature rise. Consequently we can't avoid making an assessment based on measured temperatures, despite the great difficulties involved. This is discussed next.

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3. Fact Check: CO2 emissions fingerprint on temperatures

Outcome: When accounting for possible effects on Northern hemisphere temperatures, a rather good match can be obtained when about 0.5 °C temperature increase since 1880 is ascribed to CO₂ emissions. Notably in recent years the match is much better with CO₂ than without it. As no other man-made greenhouse gasses were accounted for, here "CO₂" stands for all man-made greenhouse gasses and aerosols.

Extrapolating, we can estimate an approximately 1°C transient temperature increase in the Northern hemisphere from a doubling of CO₂. This estimation is similar to recent estimates by "moderate", non-alarmist climate scientists. However, that is without taking in account that in the Southern hemisphere the expected temperature increase should be less. In other words, based on this estimation the global average transient effect from a doubling in CO₂ may well be less than 1°C.

Outlook

From our two temperature simulations we can forecast a likely progression of temperatures in the coming years. (disclaimer: climate projections are speculative in nature!). The long term solar cooling trend (which apparently already started) should significantly reduce CO₂ warming and possibly even stabilize the temperatures for decades to come. However, that is without accounting for the short term solar oscillation with a period of about 11 years: up to the year 2025 more temperature increase can be expected. And it is speculated that after 2050 or 2060, the long term solar cycle will again turn in phase with CO₂ warming. Future sea rise may be expected to follow those temperature trends.

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[work in progress!]

Possible further aspects to check (you - yes you! - can help):

- CO2 emissions fingerprint on atmosphere: "atmospheric hotspot"

- CO2 emissions fingerprint on up going and down going infrared radiation

- testing theories on ice ages and Eocene thermal maximum

- testing competing climate theories on different planets

- CO2 effects on corals ("acidification")

- CO2 effects on plant growth ("greening"

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uploaded files: File:KNMI 6 tide gauge stations.ods

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Discussion: in the Forum you can give comments, suggestions and criticism