Case in point, a recent report on research conducted by a team at Duke University. Their paper,
Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise, was printed in the Nature. All you need to do is read the last line of the paper,
Let me explain the acronyms for you. GMT is the global mean average surface temperature. This is an observed value. EUN is the 'envelope of unforced noise.' As the authors explain, when a given model produces a result, there is a range of GMT values that represent to range of natural variability in the climate due to many different causes. RCP is the Representive Concentration Pathways. These are the different CO2 concentration scenarios used in estimates and there are four of them - RCP 2.6, 4.5, 6.0 and 8.5. The higher the number, the higher the CO2 concentration.We also find that recently observed GMT values, as well as trends, are near the lower bounds of the EUN for a forced signal corresponding to the RCP 8.5 emissions scenario but that observations are not inconsistent with a forced signal corresponding to the RCP 6.0 emissions scenario.
So, what this team did was to independently determine what the GMT was the last 1000 years and compare them to model results. They found the natural variability (unforced signal) was NOT big enough to account for the warming. Instead, they found manmade emissions (forced signal) must be included and their findings come in at the lower end of RCP 8.5, but are consistent with the RCP 6.5 scenario. In other words, they found manmade forcing (manmade emissions) MUST be included in order to get results that are consistent with actual measurements. Natural variability is not enough by itself to result in the observed warming.
Once you understand the acronyms, the conclusion is pretty clear. If you need some additional clarification, you can read the explanation provided by the paper's authors here at Real Climate. A key sentence in the explanation is,
Therefore, our results confirm that positive radiative forcings (e.g., from human-caused increases in greenhouse gas concentrations) are necessary in order for the Earth to have warmed as much as it did over the 20th century.
Therefore, our results confirm that positive radiative forcings (e.g., from human-caused increases in greenhouse gas concentrations) are necessary in order for the Earth to have warmed as much as it did over the 20th century. - See more at: http://www.realclimate.org/index.php/archives/2015/05/global-warming-and-unforced-variability-clarifications-on-recent-duke-study/#sthash.RRVLV0um.dpufSo, what did the deniers say?
Our climate models are WRONG: Global warming has slowed - and recent changes are down to ‘natural variability’, says study – Daily Mail
Happy Earth Day! The Computer Models Are Wrong! – Rush Limbaugh
New evidence against global warming: Take your pick: It's not living up to hype or not happening at all - WND
When I look at these headlines - and their sources - I ask myself, is this a case of deliberately lying or is it a case of rejecting science? Unfortunately, I can reach only one conclusion - it's both.