Add README.md

README.md

+These 4 codes can be used to estimate climate sensitivity by using the tropical
+temperature of the models participatin in the Paleoclimate Modelling 
+Intercomparison Project (PMIP).
+
+Any climate properties can replace the variables x or y, following the theory
+of emergent constraints.
+
+A detailed description of each method can be found in Renoult et al., In review
+
+For any inquiries or technical questions, please contact 
+Martin Renoult (Stockholm University)
+martin.renoult@misu.su.se
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