top of page



This rather long story is based on the research study be name “Challenging the scientific basis of the Paris climate agreement” published in International Journal of Climate Change Strategies and Management in April 2018:

The Paris Agreement or COP21 (21st Conference of the Parties) into effect on 4th November, 2016. The climate agreement was ratified by 160 countries by the end of August 2017. The Paris agreement is now legally binding but does not contain legally binding provisions.

The aim of the COP21 (2015) is to keep a global temperature increase below 2 ⁰C by 2100 and to drive efforts to limit the temperature increase even to 1.5 ⁰C above pre-industrial levels. Therefore, the emissions should be reduced to 40 GtCO2eq. In addition, the 1.5 ⁰C scenario demands that the emissions be reduced further (COP21, 2016), as anticipated in the special report to be prepared by the IPCC (Intergovernmental Panel on Climate Change) in 2018.

The emission target of 40 GtCO2eq can be compared to the global GH gas emission of 53.5 GtCO2eq in 2012. It means that the present emissions are already above the COP21 target. The global CO2 emissions of 36.3 GtCO2 in 2016 and they have been at this level during the last five years. These emissions include China 10.6 GtCO2, USA 5.3 GtCO2, and the EU 3.4 GtCO2. China’s emissions grow steadily, and it has not promised to reduce the emissions before 2030. The COP21 also includes a financing statement that the industrialized countries promise to deliver $100 billion a year of aid to developing countries for climate-related projects prior to 2025.

COP21 scientific basis

COP21 does not define the scientific basis of the agreement for the warming effects of the anthropogenic emissions, but it refers to a scenario. This scenario has not been defined in the COP21, but it can be found. The scientific resource of United Nations as well as of the COP21 is IPCC. The exact specification of IPCC is (Summary for Policymakers. In: Climate Change 2014. Mitigation of Climate Change”): “Baseline scenarios, those without additional mitigation, result in global mean surface temperature increases in 2100 from 3.7 °C to 4.8 °C compared to pre-industrial levels (range based on median climate response; the range is 2.5 °C to 7.8 °C when including climate uncertainty)”. Even though IPCC refers to multiple scenarios in the text above, the surface temperature increase to the average value of 4.25 ⁰C means one scenario only.

I analyze and challenge the COP21 science basis 1) the target value of below 2 ⁰C, 2) the scenario of the COP21, 3) the results of the IPCC’s own climate change science calculations, 4) the error of the IPCC’s climate model, 5) the water feedback, 6) the radiative forcing of carbon dioxide, and 7) the exhaustion of the fossil fuel reserves.

The first challenge: The maximum warming target of the COP21

According to the IPCC the warming above 2 °C could trigger a large-scale climatic event. Simulations using the General Climate Models (GCMs) show coral-reef bleaching, deglaciation, sea level rise, food production decrease, increase of extreme weather events, and so on, if the warming exceed 2 °C. The accuracy of GCMs is analyzed later.

The warming effects of the present time

The dreadful warming effects cannot be observed so far even though the present CO2 concentration is slightly above 400 ppm and closing the limit of 450 ppm, which should cause the runaway effect per the IPCC. The arctic sea ice amount has decreased 9-20 % and has now levelled off because of the temperature pause. The polar bears are doing well, and the population is the greatest during the last hundred years despite of numerous opposite forecasts. The deglaciation has continued. Sea level rise rate is the same as it has been for centuries. The frequency and the accumulated cyclone energy do not show increasing trend (Policlimate, 2017).  The wheat production of the world has increased steadily even in the warmest countries like India and Brazil (Faostat, 2017). India’s government reports that foodgrain production is estimated to be at an all-time high in 2016-17 (Livemint, 2017). The positive effects of CO2 can be noticed in the greening of the Earth (Zhu et al.).

The second challenge: The scenario of COP21

Four different scenarios have been defined in Assessment Report 5 (AR5, 2013) and the highest warming increase happens according to the RCP8.5, which comes from the words Representative Concentration Pathway (RCP) 8.5. The number 8.5 means the Radiative Forcing (RF) value of 8.5 Wm-2 in 2100 caused by GH gases. The warming value can be calculated according to IPCC (2013) as

dT = CSP*RF,           (1)

where dT is the global surface temperature change (K) starting from the year 1750, CSP is the climate sensitivity parameter (K/(Wm-2) and RF is the radiative forcing (Wm-2). The CSP value is 0.5 K/(Wm-2) per IPCC (2001). The temperature increase per RCP8.5 is thus 0.5 K/(Wm-2) * 8.5 Wm-2 = 4.25 K. It is the same as the mean value of the baseline scenario as described above. The RF value can be calculated according to the CO2 concentration using the Eq. (2) represented by Myhre et al. in 1998 and used by IPCC as well as by General Climate Models (GCMs)

RF = k * ln(C/280)     (2)

where k is 5.35 (Wm-2) and C is the CO2 concentration (ppm). The RF value of 8.5 Wm-2 is a result of the CO2eq concentration of 1370 ppm and it is also the same value as defined in the RCP8.5. The baseline scenario of COP21 is the worst-case scenario RCP8.5 of the IPCC.

Alternative scenario

The second challenge comes from the selection of the baseline scenario. According to the RCP8.5, CO2 concentration would be 541 ppm in 2050 and 936 ppm in 2100 (IPCC, 2007). It would mean that the average yearly growth rate of 2.2 ppm during the last 10 years should increase to the yearly growth rate of 6.4 ppm during the next 84 years, which is 2.8 times greater. The same strong growth rate increases would be needed also for methane and nitrogen oxide in order to reach 1370 CO2eq. This high CO2 growth rate can be criticized because during the last six years the CO2 emissions have stayed almost constant at the level of 35 GtCO2y-1. Therefore, the alternative baseline scenario without mitigation effects could be a “Business as usual” (BAU) scenario, which would mean keeping the CO emissions at about the present level of 40 GtCO2, and the total GH gas emissions at the level of 55 GtCO2eq.


The third challenge: The results of the IPCC’s own climate change science calculations


The author calls the equations (1) and (2) the IPCC model. In Fig. 1 is depicted the warming effect of CO2 concentration increase per equations (1) and (2), and one can see that the CO2 concentration of 590 ppm causes the warming effect of 2 ⁰C.



Figure 1. The warming effect of carbon dioxide (CO2) according to IPCC calculations. The emission rates of 50 GtCO2eq and 40 GtCO2eq are constant from 2030 onward.

According to Assessment Report 5 (AR5) of IPCC, the RF value of GH gases in 2011 was 2.29 Wm2, and this RF value has increased to 2.44 Wm-2 according to NOAA in 2016. It corresponds to the warming value of 1.22 ⁰C, which would mean the CO2eq value of 442 ppm. The United Nations Framework Convention on Climate Change (UNFCCC) manifests on their web page that the CO2eq concentration must not exceed 450 ppm to stay under 2 ⁰C. As one can see in Fig. 1, the 450 ppm of CO2eq would cause a temperature increase of 1.27 ⁰C, which is far below 2 ⁰C. This is a piece of conflicting information of the COP21.


Using the IPCC’s climate model, the real CO2 concentration needed for 2 ⁰C is 590 ppm. The present growth rate is about 2.2 ppm per year which would mean quite exactly the concentration of 590 ppm in 2100. The conclusion is that using the IPCC’s own model and the BAU scenario, the warming limit would not happen before 2100.

The fourth challenge: The error of the IPCC’s climate model

In Fig. 2 are depicted the observed temperatures and the IPCC model calculated temperatures. As known the GCMs show practically the same warming values for the present times as the IPCC’s model, because the warming effects are based on the equations of (1) and (2).



Figure 2.  The observed temperature changes since 1880 according to different data sets and publications, and the IPCC model calculated temperatures. The temperatures are 11 years running mean values except the last five years, where the future temperatures are not known.

Without going into detail analysis,


Figure 2 shows the problems with the temperature measurements and the error of the IPCC’s climate model. The graph of National Academy of Sciences (NAS) published in 1975 shows temperature peaks in the 30’s and 40’s. In the newer temperature data sets by GISS (2008), and GISS (2017) this peak has almost disappeared. The greatest changes in the historical temperatures have happened in the latest version of GISS 2017. The satellite based temperature measurements (UAH, 2017) show practically no warming trend since 2000. The UAH temperature data starts from 1979 and it has been equalized to be the same as GISS 2017 in 1979-1981. The further warming of GISS 2017 version during 2010s seems to be about 0.2 ⁰C in comparison to the UAH temperature.


The IPCC model calculated temperature for 2016 is 1.27 ⁰C. It is 49 % higher than 0.85 ⁰C, which is the average temperature during the pause since 2000 according to AR5. The year 2016 was the warmest and the strongest El Nino event during the direct measurement history but now the temperature has decreased almost back to the average level (UAH). The big difference between the IPCC model and the observations considerably weakens the reliability of the baseline scenario, because they are based on the very same calculations and the difference is already intolerable. It should be remembered that IPCC states in the AR5 that it is extremely likely that more than half of the observed temperature increase from 1951 to 2010 was due to the anthropogenic GH gases leaving an opportunity for natural causes.


The fifth challenge: The water feedback

The strength of CO2 as a GH gas is normally expressed as a climate sensitivity (CS), which is the global warming caused by the CO2 concentration doubling from 280 ppm to 560 ppm. IPCC reports in AR4 (IPCC, 2007b) that water vapor roughly doubles the response to forcing of GH gases and it is called positive water feedback. The TCS (Transient CS) of IPCC includes water feedback and this feature is inherently in the CSP value 0.5 K/(Wm-2) used by IPCC. I have calculated the CSP value (Ollila, 2014) using the energy balance of the Earth and the result was 0.268 K/(Wm-2) and the method of spectral analysis gave the CSP value 0.259 K/(Wm-2). These results can be rounded to 0.27 K/(Wm-2), and it means that the amount of water in the atmosphere is constant having no positive or negative feedback.

The TCS definition resumes that the increase rate of CO2 concentration is of maximum 1 %/y. The TCS can be calculated using equations (1) and (2), which give the value 1.85 ⁰C. In the IPCC’s report AR5 (IPCC, 2013) TCS is between 1.0 to 2.5 ⁰C and it means the average value of 1.75 ⁰C, which is very close to 1.85 ⁰C. It should be noticed that values are calculated using the CSP value of 0.5 K/(W/m-2) applicable for TCS calculation and the 1 %/y CO2 growth rate limit has not been exceeded.

The best evidence about the existence of positive water feedback can be found in the direct humidity measurements. Rather reliable conclusions about the water feedback can be drawn from the behaviour of the climate since 1979. The encompassing satellite temperature measurements were introduced in 1979 (UAH, 2017). In the same year a new humidity semiconductor sensor technology Humicap® was introduced by the leading humidity measurement company Vaisala.

The temperature according to the UAH satellite data set and absolute humidity (TPW) values from NOAA’s NCEP/NCAR Reanalysis dataset (2017) are depicted in Figure 3. The warming impacts of water are calculated based on the spectral analysis calculations (Ollila, 2017) by increasing the water content of the average atmospheric conditions (2.6 prcm / 305.978 Wm-2). The short-term temperature changes are distinctly related to the El Niño / La Niña events, which are caused by the regional changes of the currents and winds in the tropical central and eastern Pacific Ocean. They initiate the temperature change, and the strong change of absolute humidity amplifies the change by a factor of about 100 percent. It is practically the same as the positive feedback used by IPCC, but can it be found in the long-term trends?


Figure 3. The temperature, absolute humidity, and the water warming impact trends in the atmosphere since 1979.


There are essential features in the long-term trends of temperature and TPW, which are calculated and depicted as 11 year running mean values. The long-term value of temperature has increased by about 0.4 ⁰C since 1979 and now it has paused at this level. The long-term trend of TPW shows a minor decrease during the temperature increasing period from 1979 to 2000, and thereafter only a small increase during the present temperature pause period. It means that the absolute water amount of the atmosphere is practically constant, reacting only very slightly to the long-term trends of temperature changes and not according to the positive water feedback theory. Long-term changes, which last at least one solar cycle (from 10.5 to 13.5 years), are the shortest period to be analyzed in the climate change science. The conclusion is that RH is not constant in the atmosphere.

The sixth challenge: The radiative forcing of carbon dioxide

The question is, can the positive water feedback be confirmed by the real observations and is the RF value of equation (2) reported by Myhre et al. correct?

I have reproduced the RF value of Myhre et al. utilizing the same spectral analysis method (Ollila,2014). The result of this study is that the RF value can be calculated using the same kind of logarithmic formula, but the coefficient k is different:

RF = 3.12 * ln(C/280)       


Using the CSP value of 0.27 K/(Wm-2) and equation (3) gives ECS value 0.6 ⁰C only. Abbot and Marohasy (2017) have used six temperature proxy datasets and an artificial neural network to create temperature projections through the 20th century. Based on the deviations between the projections and the measured temperatures, their estimate for ECS is 0.6 ⁰C.  In Fig. 4 is depicted the observed temperature as the combination of GISS 2008 from 1880 to 1979 and UAH from 1979 to 2016 as well as the temperature trends of different scenarios.


Figure 4. The temperature effects of different climate models. All scenarios are fitted to start from the observed 11 years running mean temperature in 2016.

In Fig. 4 is also depicted the baseline scenario of COP21 per the IPCC calculations and per Ollila calculations, two scenarios of 40 GtCO2eq from 2030 onward according to the IPCC’s model and according to my research studies. In three scenarios, the temperature increase would stay below the upper temperature target of 2 ⁰C.


The seventh challenge: The exhaustion of the fossil fuel reserves

The baseline and BAU scenarios can be evaluated against the fossil fuel reserves estimated to be available utilizing the conventional technology. The estimates of BP are: coal 1139 GtC, natural gas 168 GtC, and oil 201 GtC.If the production and consumption of fossil fuels continue with the present rates, the reserves would be exhausted for coal by 2169, natural gas by 2068, and oil by 2066 according to BP. Considering these estimates, even the BAU scenario seems to be realistic only until 2060s. The baseline scenario would mean the utilization of new unconventional technologies making the oil and gas prices after 2050s much higher than today.

The challenges of the Paris climate agreement are:

1) The target value is based on climate model calculations, which cannot be tested for 100 years’ time span.

2) The baseline scenario of COP21 is unrealistic (CO2 growth rate 6.4 ppm per year). A better scenario would be the “Business as usual” (BAU) based on the present CO2 growth rate of 2.2 ppm per year.

3) The results of the IPCC’s model show that the warming would stay below 2.0 ⁰C if the scenario would be the BAU.

4) The error of IPCC’s climate models is today about 50 %.

5) The direct humidity measurements show that Relative Humidity is not constant and thus the positive water feedback does not exist.

6) The critical climate change studies show that the warming according to IPCC’s model is about 200 % too great. The missing positive water feedback would alone decrease the warming rate by 50 % and because of this, the warming rate would stay below 2.0 ⁰C even according to the baseline scenario.

7) The known conventional oil and gas reserves would be exhausted by 2070s by the present consumption rate. The experience so far is, that the oil companies have been able to find new reserves or to develop new technologies for unconventional reserves. The Roman Club predicted that the oil and gas reserves will be exhausted in 1992 and 1993.


Zhu, Z., et al., 2016. Greening of the earth and its drivers. Nature Climate Change, 

Policlimate, (2017). Global tropical cyclone activity,

Faostat, (2017), Production quantities of Wheat in World,

Livemint, (2017). Foodgrain production estimated at a record 272 million tonnes in 2016-17:govt,

Ollila, A. 2014. The potency of carbon dioxide (CO2) as a greenhouse gas. Dev. Earth Sci. 2, 20-30,

Ollila, A. 2017. Semi empirical model of global warming including cosmic forces, greenhouse gases, and volcanic eruptions. Phy. Sci. Int. J. 15(2), 1-14,

Ollila, A. 2018.  Challenging the scientific basis of the Paris climate agreement,


Lämpötilamuutos 1979-2015 - ajavat voima
bottom of page