You have an example of usage of try + infinitive and that's where your attention should focus although the tense does change the meaning. In general, try + infinitive means that the action with the verb in the infinitive has not been completed. Try + gerund implies that the action is completed. In both cases, the implication is that there is failure.
Look at these examples:
I try to tell him the truth, but I was overwhelmed emotionally and couldn't manage it.
I tried telling him the truth, but he didn't believe me.
These days lots of scientists try to solve the problem of pollution.
The meaning here is that they try to solve but then they either abandon the cause or do not find solutions.
These days lots of scientists are trying to solve the problem of pollution.
This means that scientists are in the effort. To this point, no solution has been found, but in the future that may not be so. Scientists are trying but have no idea if they will succeed or not.
These days lots of scientists have been trying to solve the problem of pollution.
Just as the present perfect continuous tense implies, this would be an action that has been happening up until now or is still continuing beyond this point. The difference between this and the present continuous is that the implication is that this has been happening for someone time. If stated in the present continuous, one might understand that scientists have only recently started. Whereas with the present perfect continuous, the idea is that they have been working on this for a while. However, in terms of the future, the idea is the same as the present continuous. That is, they are trying, but have no idea whether they will actually succeed.
Also, don't forget that you need a comma after "These days".