Climate Change Past to Present

1. Based on the readings the general synopsis of the research is that the warming of the recent 1,500 years or so are unprecedented, meaning not that it is simply not consistent with the past patterns. The research used data from 73 temperature stations around the world and have been able to pretty accurately reconstruct the Earth's climate since the last ice age, and fairly well of the past ~11,300 years. The research shows that the Earth's temperatures have been warmer recently than it has been over that last ~11,300 years, approximately warmer than ~75% of the time period. The most critical piece of the paper examines future climate changes and projects that by the year 2100 the temperatures will exceed the previous maximums of the Halocene period under possible scenarios influenced by greenhouse emissions.

2. The three key findings of the study are as follows:
     - Over the past ~5,000 years the Earth has cooled ~1.3 degrees F, but in the past ~100  years it has warmed ~1.3 degrees F (mainly in the North where more land masses and human life exists).
     - The temperatures over the whole Halocene period are warmer now more than about ~75% of the last ~11,300 years, which is the span of human existence as far as we know.
     - Finally, there is the prediction that temperatures will rise another 2.0-11.5 degrees F by the end of the century (the year 2100), saying that it is largely dependent on the amount of carbon emissions in the upcoming years.

3. They key graph shows the overall changes and prospective changes that have and could occur to our planet in terms of global temperature. There is a clear sign that the temperatures have decreased previous to the current period, but now there seems to be a sharp increase heading into this century. The projections are also shown and is visible that the temperatures are expected to rise past the highs of the Halocene period, within the century.

Figure 1:Information above explains the graph. 

Source: http://planet3.org/wp-content/uploads/2013/03/marcott-B-1000-500x342.jpg

4. Michael Mann argues that the take home point of the study is that the rate and magnitude of recent global warming is unprecedented in the past ~4,000 years, and in the past ~11,000 years the rate is unprecedented. This means that there is a noticed increase that not only seems to be going past the highs of the past, but also that the rate at which the temperature is increasing is something so sharp that has not been seen before, and could be rising to levels higher than ever before.

5. Robert Rohde expresses concerns for the magnitude of the warming based on the study. He says that the magnitude of the estimated warming is slightly larger than he had previously believed and that this can be useful when trying to understand and learn the past magnitude of changes and how forcing and other factors work in affecting global warming or change. He does have one issue with the study finding that the high frequency variability is suppressed and therefore it is hard to make connections and comparisons between rapid changing events like the warming in the past century.

6. Richard Alley says the big picture of the study is that we want to know if past warming or cooling was natural and if the changes of temperature were faster or slower than previous. He says that the recent changes do not necessarily project the changes now perfectly and if there were an error in determining the past changes, then it could affect our predictions to either be better or worse than what could actually occur.

7. Roger Pielke Jr. says that the data was grossly misused in terms of representing the data to the public. In the graph above there is a spike in the data since about the 1900's, but Pielke says that anything past 1900 cannot be concluded. This graph makes predictions which is not data and can be quite misleading, so he suggests that we fix the mistake to not include the spike until we actually have conclusive data to support such predictions.