As we have seen, there is already concern that global warming will cause significant melting of the polar ice caps. This will lead to more fresh water being added to the polar oceans. Climate change could, therefore, cause the collapse of the NADW, and a weakening of the warm Gulf Stream (Figure 31b). This would cause much colder European winters and more severe weather. However, the influence of the warm Gulf Stream is mainly seen in the winter and has only a small effect on summer temperatures. So, if the Gulf Stream fails, global warming would still cause European summers to heat up.
